Proto-Albanian language

Proto-Albanian is the ancestral reconstructed language of Albanian, before the Gheg–Tosk dialectal diversification (before c. 600 CE). Albanoid and other Paleo-Balkan languages had their formative core in the Balkans after the Indo-European migrations in the region. Whether descendants or sister languages of what was called Illyrian by classical sources, Albanian and Messapic, on the basis of shared features and innovations, are grouped together in a common branch in the current phylogenetic classification of the Indo-European language family. The precursor of Albanian can be considered a completely formed independent IE language since at least the first millennium BCE, with the beginning of the early Proto-Albanian phase.

Proto-Albanian is reconstructed by way of the comparative method between the Tosk and Gheg dialects and between Albanian and other Indo-European languages, as well as through contact linguistics studying early loanwords from and into Albanian and structural and phonological convergences with other languages. Loanwords into Albanian treated through its phonetic evolution can be traced back as early as the first contacts with Doric Greek (West Greek) since the 7th century BCE, but the most important of which are those from Latin (dated by De Vaan to the period 167 BCE to 400 CE) and from Slavic (dated from 600 CE onward). The evidence from loanwords allows linguists to construct in great detail the shape of native words at the points of major influxes of loans from well-attested languages.

In historical linguistics Proto-Albanian is broken up into different stages which are usually delimited by the onset of contact with different well-attested languages. Pre-Proto-Albanian is the early stage of the precursor of Albanian during the first millennium BCE, marked by contacts with Ancient Greek, but not yet by contacts with Latin. Proto-Albanian proper is dated to the period of contacts with Latin, starting from the 2nd century BCE after the Roman conquest of the Western Balkans, but the major Latin influence occurred since the first years of the common era when the Western Balkans were eventually incorporated into the Roman Empire. Common Albanian or its two dialects, Proto-Gheg and Proto-Tosk, experienced the earliest contacts with South Slavic languages since the Slavic migrations to the Balkans in the 6th–7th centuries CE. The rise of Tosk from Proto-Albanian was prompted before Slavic contacts circa 600 CE, as evidenced by the fact that Latin and ancient Greek loanwords are treated like native words with regard to taxonomical differences between Gheg and Tosk, but the same is not true of Slavic loans.

History
Albanoid and other Paleo-Balkan languages had their formative core in the Balkans after the Indo-European migrations in the region about 3000 to 2500 BCE. They replaced the pre-Indo-European languages, which left traces of the Mediterranean-Balkan substratum. Shortly after they had diverged from one another, Pre-Albanian, Pre-Greek, and Pre-Armenian underwent a longer period of contact, as shown by common correspondences that are irregular for other IE languages. Furthermore, intense Greek–Albanian contacts have continued thereafter.

The precursor of Albanian can be considered a completely formed independent IE language since at least the first millennium BCE, with the beginning of the early Proto-Albanian phase. The precursor of Albanian is often thought to have been an Illyrian language for obvious geographic and historical reasons as well as for some linguistic evidence,
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.
 * or otherwise an unmentioned Balkan Indo-European language that was closely related to Illyrian and Messapic. Messapic, which is grouped in the same IE branch of Albanian, developed in southeast Italy after crossing the Adriatic Sea at least since the Early Iron Age, being attested in about six hundred inscriptions from Iron Age Apulia.

In classical antiquity Proto-Albanian was spoken in the central-western part of the Balkan Peninsula, to the north and west of the Ancient Greeks, as shown by early Doric Greek (West Greek) and Ancient Macedonian loanwords that were treated with characteristic Albanian features, by classical place names exclusively observing Albanian accent and phonetic rules, as well as by several Proto-Albanian items preserved in ancient glossaries.

Contacts with Ancient Greek
Proto-Albanian speech came into contact in its earlier stage with Ancient Greek since the 7th century BCE, when the Greek colonies were founded on the Adriatic coast of Albania. In that period early loanwords were borrowed from Doric Greek (West Greek), either directly from the colonists or indirectly through trade communication in the hinterland. During the 5th–4th centuries BCE Proto-Albanian directly loaned words from Ancient Macedonian, at a time when this language gained prominence in the region and was not yet replaced by Koine Greek. Several Proto-Albanian terms have been preserved in the lexicon of Hesychius of Alexandria and other ancient glossaries. Some of the Proto-Albanian glosses in Hesychius are considered to have been loaned to the Dorik Greek as early as the 7th century BCE.

Evidence of a significant level of early linguistic contact between Albanian and Greek is provided by ancient common structural innovations and phonologic convergence such as: Those innovations are limited only to the Albanian and Greek languages and are not shared with other languages of the Balkan sprachbund. Since they precede the Balkan sprachbund era, those innovations date to a prehistoric phase of the Albanian language, spoken at that time in the same area as Greek and within a social frame of bilingualism among early Albanians having to be able to speak some form of Greek.
 * the rise of the close front rounded vowel /y/ (documented in Attic and Koine Greek);
 * the rise of dental fricatives;
 * the voicing of voiceless plosives after nasal consonants;
 * the replacement, with a form that featured a prefix, of the inherited present tense 3rd person singular of the verb "be" (documented in Koine Greek).

Contacts with Latin, Romance, and Middle Greek


Proto-Albanian came into contact with Latin since the Illyro–Roman wars in the late 3rd and early 2nd centuries BCE, when the Roman Republic defeated the Illyrians and began to establish its rule in the Western Balkans, gradually consolidating its dominion during the last two centuries BCE. But the major Latin influence in Proto-Albanian occurred since the first years of the common era, when the Western Balkans were eventually incorporated into the Roman Empire after the Great Illyrian Revolt of 6–9 CE (Bellum Batonianum).

The Latin loanwords in Proto-Albanian were borrowed through the entire period of spoken Latin in the Western Balkans (c. 167 BCE–400 CE), reflecting different chronological layers and penetrating, without any restrictions, into virtually all semantic fields. Even the basic Christian terms are of Latin origin, and since they entered Proto-Albanian before the Gheg–Tosk dialectal diversification, the Proto-Albanian speakers were christianized under the Latin sphere of influence, specifically in the 4th century CE.

Historical linguistic considerations indicate that the Roman province of Moesia Superior, and more specifically the ancient region of Dardania and adjacent zones, constitute the best candidate for the area where Proto-Albanian received its major Latin influence, and where intensive contacts between Proto-Albanian and Proto-Romance occurred, eventually producing the shared innovations between Tosk Albanian and (Proto-)Romanian. Those innovations ultimately prompted the rise of Tosk from Proto-Albanian, a diversification that began not later than the 6th–7th centuries CE (i.e. before the period of contacts with Slavic). Gheg Albanian was already separated from the Albanian–(Proto-)Romanian contact zone at an earlier period. Toponymy provides evidence that Albanian was already spoken since late antiquity in northern and central Albania, but not yet in southern Albania (south of the Shkumbin river). Those considerations indicate that unlike Gheg, the Tosk dialect could not yet have already occupied its historical geographic distribution in late antiquity. On the other hand, the multi-layered Albanian dialects in western North Macedonia provide evidence that the area was inhabited by Albanian-speakers since antiquity. The historical geographic spread of the Albanian dialects as it appeared in medieval times is considered to have been shaped by the settlement of Slavic farmers from the 6th–7th centuries CE.

During the centuries of the Great Migration Period in the Roman Empire after the 3rd century CE, the Imperial structures progressively weakened and eventually collapsed. Proto-Albanian and Proto-Romanian speakers remained in close contact for a substantial time frame as mountain pastoralists. The fact that the Albanian language reflects a clear pastoralist stage does not allow conclusions about the Proto-Albanian speakers' way of life during classical antiquity, as only the speech of the mountain pastoralists managed to survive the Great Migrations. It has been suggested that the Latin influence on Albanian resulted from a urbanized way of life, which was followed by a flight from towns similar to what occurred to the Eastern-Romance speakers. Nevertheless, the extensive influence of the Albanian language on the pastoral vocabulary and its influence, albeit lower, on the crop cultivation vocabulary, in Eastern Romance languages, indicate that Proto-Albanian speakers were already leading a pastoral lifestyle at the time when Latin speakers assumed the same way of life, borrowing from (Proto-)Albanian a number of technical terms.

The post-Roman contact zone between Albanian and Common Romanian is considered to have been located in Dardania and adjacent areas. From this contact the Tosk Albanian dialect is considered to have received the first impetus of developments that were shared with Eastern Romance and that did not affect the Gheg Albanian dialect as it had already separated in earlier times. After a period of common innovations, but before the rise of the rhotacism n > r (which preceded contacts with Slavic from c. 600 CE), speakers of Eastern Romance varieties that were not yet affected by this fundamental sound change separated from the Tosk Albanian–Common Romanian contact zone. In a period that followed the rise of those innovations, Tosk Albanian is considered to have moved – driven by the offensive of the Slavs – to Albania south of the Shkumbin river in its historically documented location.

At the time of the South Slavic incursion and the threat of ethnic turbulence in the Albanian-inhabited regions, the Christianization of the Albanians had already been completed and it had apparently developed for Albanians as a further identity-forming feature alongside the ethnic-linguistic unity. Church administration, which was controlled by a thick network of Roman bishoprics, collapsed with the arrival of the Slavs. Between the early 7th century and the late 9th century the interior areas of the Balkans were deprived of church administration, and Christianity might have survived only as a popular tradition on a reduced degree. The reorganization of the Church as a cult institution in the region took a considerable amount of time, as the Balkans were brought back into the Christian orbit only after the recovery of the Byzantine Empire and through the activity of Byzantine missionaries.

The earliest ascertained church vocabulary of Middle Greek origin in Albanian dates to the 8th–9th centuries, at the time of the Byzantine Iconoclasm, which was started by the Byzantine Emperor Leo III the Isaurian. In 726 Leo III established de jure the jurisdiction of the Ecumenical Patriarchate of Constantinople over the Balkans, as the Church and the State established an institution. The Eastern Church expanded its influence in the area along with the social and political developments. Between the 7th and 12th centuries a powerful network of cult institutions were revived completely covering the ecclesiastical administration of the entire present-day Albanian-speaking compact area. In particular an important role was played by the Theme of Dyrrhachium and the Archdiocese of Ohrid. The lack of Old Church Slavonic terms in Albanian Christian terminology shows that the missionary activities during the Christianization of the Slavs did not involve Albanian-speakers, indeed, the Christian belief among Albanians had survived through the centuries and already become an important cultural element in their ethnic identity.

Earliest contacts with South Slavic
When the Slavic-speaking farmers migrated to the Balkans and settled the plains from the 6th–7th centruries CE, they encountered Albanian-speaking Indo-Europeans and assimilated part of them, but the language of the Albanians who had taken refuge in the mountainous areas of present-day northern and central Albania, eastern Montenegro, western North Macedonia, and Kosovo, managed to survive the Great Migrations. Leading a pastoral lifestyle and although separated from Slavic-speakers, Albanian-speakers were not isolated, and contacts between Albanian and Slavic occurred thereafter. In particular, Tosk Albanian came into contact with Eastern South Slavic dialects, and Gheg Albanian with Western South Slavic dialects. Early long-standing contacts between Slavic-speakers and Albanian-speakers might have been common in mountain passages and agriculture or fishing areas, such as the valleys of the White and Black branches of the Drin and around the Shkodër and Ohrid lakes. Such contacts in these areas caused many changes in Slavic and Albanian local varieties.

As Albanian and South Slavic have been in contact since the early Middle Ages, loanwords in both belong to different chronological strata and reveal different periods of acquisition. The earliest phase of contacts is dated to the 6th–8th century CE, reflecting some of the more archaic phonetic features of Slavic as well as early Albanian phonology. The early Slavic loanwords into Albanian developed Slavic *s as /ʃ/ and *y as /u/ within Albanian phonology of that era. Such toponyms include Bushtricë (Kukës), Dishnica (Përmet), Dragoshtunjë (Elbasan), Leshnjë (Leshnjë, Berat and other areas), Shelcan (Elbasan), Shishtavec (Kukës/Gora), Shuec (Devoll) and Shtëpëz (Gjirokastër), Shopël (Iballë), Veleshnjë (Skrapar) and others. Part of the toponyms of early Slavic origin were acquired in Albanian before undergoing the changes of the Slavic liquid metathesis (before c. end of the 8th century CE). They include Ardenicë (Lushnjë), Berzanë (Lezhë), Gërdec and Berzi (Tiranë) and a cluster of toponyms along the route Berat-Tepelenë-Përmet.

The evolution of the ancient toponym Lychnidus into Oh(ë)r(id) (city and lake), which is attested in this form from 879 CE, required an early long-standing period of Tosk Albanian–East South Slavic bilingualism, or at least contact, resulting from the Tosk Albanian rhotacism -n- into -r- and Eastern South Slavic l-vocalization ly- into o-. The name of the region Labëri resulted through the Slavic liquid metathesis: South Slavic *Labanьja < Late Common Slavic *Olbanьja 'Albania', and was reborrowed in that form into Albanian, in the period when rhotacism was still active in Tosk Albanian.

History of study
Vladimir Orel is one of the main modern international linguists to have dealt with the passage from Proto-Indo-European to Proto-Albanian to Modern Albanian. According to Orel, the study of Proto-Albanian syntax remains in its infancy so there are some limitations to the work. However, there have been developments in the understanding of the historical development of phonetics and vocabulary. Other major work has been done by Eqrem Çabej and Shaban Demiraj as well as by major scholars in the field of Romanian historical linguistics as it relates to Albanian (see Albanian–Romanian linguistic relationship) as well as other Balkan linguists. A large amount of work done on Proto-Albanian is published in German, rather than English.

Nomenclature of periodization of Proto-Albanian
Vladimir Orel distinguishes the following periods of Proto-Albanian: 1) "Early Proto-Albanian" (EPA): spoken before the 1st century CE, when Albanian had not yet acquired extensive influence via language contact from Latin/Proto-Romance. 2) "Late Proto-Albanian" (LPA): after extensive Latin contact, with the end of the period seeing contacts between ancient Slavic idioms still close to the Proto-Slavic language, in the 6th and 7th centuries CE. During this period the structure of Proto-Albanian was "shattered" by major changes.

Ranko Matasović distinguishes the following periods of Proto-Albanian: 1) "Pre-Proto-Albanian": essentially equivalent to Vladimir Orel's "Early Proto-Albanian", except that the newer paradigm of Matasović dates Latin/Albanian contact a century earlier, and thus it ends for Matasović in the 1st century BCE rather than the 1st century CE. After this period ends, Latin contact begins to transform the language. 2) "Early Proto-Albanian": corresponds to the earlier phases of what is for Orel "Late Proto-Albanian". For Matasović, the period spans the 1st century BCE to the 6th century CE, halting before contact with Slavic idioms begins. 3) "Late Proto-Albanian": includes the last two centuries of LPA for Orel, plus most of the unattested period of "Old Albanian", halting before Turkish influence begins. In this paradigm, Gheg and Tosk split from Early Proto-Albanian, not Late Proto-Albanian, consistent with our knowledge that the split preceded Slavic contact. 4) "Early Albanian": corresponds to the late, Ottoman, phase of Old Albanian in the traditional paradigm, ending in 1800, at which point it transitions to Modern Albanian.

Demiraj, like Matasović and unlike Orel, observes the 5th/6th centuries as a boundary between stages, but instead places the "emergence of Albanian" from its parent after this point, rather than the 14th.

In an Albanian chapter penned by Michiel de Vaan within Klein, Joseph and Fritz' 2018 Handbook of Comparative and Historical Indo-European Linguistics, Demiraj's periods are adhered to. Orel's "Later Proto-Albanian", which is for them also definitively placed before Slavic contact, is referred to as simply "Proto-Albanian" (PAlb) or, in German, "Uralbanisch", reflecting the terminology of earlier writing in German. What is for Orel "Early Proto-Albanian" (EPA), dated definitively before the onset of Latin contact, is for De Vaan, "Pre-Proto-Albanian" (PPAlb); in German, this stage is called "Voruralbanisch" or "Frühuralbanisch". De Vaan also discusses the possibility of breaking "Pre-Proto-Albanian" into two stages: one before the first Greek loanwords, and one that is after the first Greek loanwords, but before contact with Latin.

This page at present is using the paradigm of Orel.

Phonology
Extensive recent studies on Proto-Albanian phonology have been published by Huld (1984), Beekes (1995), Shaban Demiraj (1996), Bardhyl Demiraj (1997), Orel (2000), Hock (2005), Matzinger (2006), Vermeer (2008), Schumacher (2013), and De Vaan (2018).

At present, this page follows Orel's paradigm for periods of Proto-Albanian, and presents the relationship between the synchronic phonologies of both "EPA" and "LPA" with diachronic relationships to each other and to ancestral Indo-European forms as well as descendant Albanian forms.

Stress
In Early Proto-Albanian, stress was paradigmatic, and behaved according to morphological class, with a base on the first syllable. In different paradigms, the stress pattern was varyingly barytonic, oxytonic, and mobile. Unstressed vowels lost one mora—long vowels were shortened, already short vowels were often deleted. In Later Proto-Albanian, however, a new system of unstressed vowel reduction emerged where *a reduced to *ë while all others were simply deleted (except for post-tonic inlaut vowels, which became *ë). Orel gives the following examples:


 * EPA *dáusas "ram" (sg) > *dauš > ... > modern dash
 * EPA *dáusai "rams" (pl) > *dauši > ... > modern desh
 * EPA *dwáigā "branch" (sg) > *déga > ... > modern degë
 * EPA *dwáigāi "branches" (pl) > *dégai > ... > modern degë

Vowels
Early Proto-Albanian possessed four distinctive short vowels: *a, *e, *i and *u. Proto-Indo-European *o had merged into *a by the Early Proto-Albanian stage. A five-way distinction was maintained for long vowels: *ā, *ē, *ī, *ō, and *ū. Early Proto-Albanian also had four diphthongs: *ei, *ai, *eu and *au.

Early Proto-Albanian's vowel inventory began to change as a result of Latin contact. Initially Albanian was resistant to the restoration of short *o as a separate phoneme, with Latin unstressed *o being replaced by *a, and stressed Latin *o being replaced by *u. However, in later loans, Latin *o is maintained in Albanian as *o. Additionally, some Latin loans with short *u saw Latin *u replaced by *o, as well as *ə specifically in unstressed positions before sonorants. In two cases, Orel argues that Latin short /u/ was lengthened in Albanian to /u:/, ultimately to render /y/. On the other hand, whatever effect Ancient Greek loanwords had at their time of absorption is unclear, but diachronically the vowels always agree with regular internal Albanian developments.

Late Proto-Albanian

Late Proto-Albanian exhibited *a, *i and *u throughout its development as distinctive short vowels. *o was restored to the phonemic inventory as a result of loanwords where it was increasingly maintained instead of replaced. Although *e was eliminated by breaking to *ie (which would render je and ja), it was restored by the leveling of /ai/ to /e/ and other phenomena that replaced /a/, /ie/, and /ue/ with /e/. The only long vowel preserved in its original form was *ī. *ō was replaced by *ue, *ē was merged into *ā and both were rounded and eventually raised to *o, while *ū merged with the diphthong *ui, ultimately rendering *y. By Late Proto-Albanian, all the original Indo-European diphthongs had now leveled, but new diphthongs were absorbed in loans, and were also innovated by breaking phenomena: *ie, *ue and *ui. *ai in Latin words with AE shared the fate of inherited Early Proto-Albanian *ai, becoming *e, while Latin AU similarly shared the fate of inherited *au and became *a.

Phonemically nasal vowels emerged in Late Proto-Albanian. First, all vowels standing before nasal consonants were nasalized. The following nasal consonant was then lost in certain morphological contexts, while the vowel remained nasalized, resulting in the emergence of LPA phonemes denoted *â, *ê, *î, and *û. Except in certain Gheg varieties, *ê merged into *â. The traditional view presented by Orel and Desnickaja is that distinctive nasalization was lost by Tosk but retained by Gheg and that this is a taxonomical difference between the two. However this has now been challenged, after Sheper and Gjinari discovered Lab dialects (Lab is a subdialect of Tosk) in the Kurvelesh region that still had distinctive nasal vowels, and Totoni likewise found that the Lab speech of Borsh also still has nasal vowel phonemes. This means that, instead of the traditional view, it is possible that denasalization happened in most Tosk dialects only after the split from Gheg.

Slavic *ū appears to still have been back and round when it was loaned into Albanian, but it is after the diphthongization and resulting fronting of the original Early Proto-Albanian *ū to *y was no longer absorbing new *ū segments, as they are, with only three exceptions, reflected as *u. Slavic *o had already become *a in the Slavic languages that contacted Albanian by the time of contact, and was loaned as *a for the most part; as is reflected also in other non-Slavic languages absorbing these words. After /v/, this *a became *o again in two attested cases: kos ("yogurt", from Proto-Slavic *kvasъ) and vorbë ("clay pot").

It was at the end of the LPA period that length became no longer distinctive in Albanian, although many Gheg and some Lab dialects preserved it and/or re-innovated it. Furthermore, by Old Albanian, all diphthongs had been lost: those ending in -i were all leveled, the -u was lost in those ending in -u, and those ending in -e were converted to glide + vowel sequences; further changes including the frequent effacement of the former first element or otherwise its hardening into an occlusive (typically /v/ for former u-, and gj /ɟ/ for former i-) rendering the former presence of a diphthong rather opaque in many reflexes.

Diachronic development
This table differentiates short vowels form long vowels with the IPA symbol <ː> being applied to the long vowels.

Specifically contextualized reflex results are placed in parentheses.

Development of Indo-European sonorants
The nasal sonorants *n̥ and *m̥ both rendered Early Proto-Albanian *a, which remains *a in modern Albanian (PIE *ǵʰh₂éns "goose" > EPA *gatā > Alb gatë "heron"). Like EPA *a elsewhere, in some cases it was raised to *e, as seen in PIE *h₁ln̥gʷʰtós > EPA *lekta > Albanian lehtë (suffixed with -të).

The development of IE dorsal consonants in Albanian
Indo-European languages are traditionally divided into two groups based on the development of the three series of dorsal (often called "guttural") stops, viz. the palatal (*ḱ *ǵ *ǵʰ), velar (*k *g *gʰ) and labiovelar (*kʷ *gʷ *gʷʰ) series. In the "centum" languages (e.g. Italic languages, Germanic languages, Greek) the palatal series has merged with velar series, while the labiovelar series remained distinct; whereas in the "satem" languages (Indo-Iranian languages, Balto-Slavic languages), the labiovelars merged with the plain velars, while the palatals shifted to sibilant consonants.

Many Indo-Europeanists have classified Albanian as a satem language since it has dental fricatives /θ/ and /ð/ as the common reflex of the palatal series, while velar and labiovelar stops in most cases have merged. However, there is clear evidence that all three IE dorsal series remained distinct (at least before front vowels) in Proto-Albanian: In the later phonologocal history of Albanian, the velars /k/ and /g/ were subject to further palatalizations.
 * *ḱ > /θ/, *ǵ/*ǵʰ > /ð/
 * *k > /k/, *g/*gʰ > /g/
 * *kʷ > /s/ (before high vowels), /k/ (elsewhere); *gʷ/*gʷʰ > /z/ (before high vowels), /g/ elsewhere.

The (partial) retention of the Proto-IE three-way contrast for dorsal stops is an archaic feature that links Albanian with the wider Paleo-Balkanic group and is shared with Messapic and Armenian.

Classification & isoglosses with other Indo-European branches
The closest language to Albanian is Messapic, with which it forms a common branch titled Illyric in Hyllested & Joseph (2022). Hyllested & Joseph (2022) in agreement with recent bibliography identify Greco-Phrygian as the IE branch closest to the Albanian-Messapic one. These two branches form an areal grouping – which is often called "Balkan IE" – with Armenian. Hyllested & Joseph (2022) identify the highest shared number of innovations between (Proto-)Albanian and (Proto-)Greek.

Innovative creations of agricultural terms shared only between Albanian and Greek, such as *h2(e)lbh-it- 'barley' and *spor-eh2- 'seed', were formed from non-agricultural Proto-Indo-European roots through semantic changes to adapt them for agriculture. Since they are limited only to Albanian and Greek, they can be traced back with certainty only to their last common Indo-European ancestor, and not projected back into Proto-Indo-European. A remarkable Greek/Albanian isogloss is a very ancient form for "hand": *mər-, cf. the Albanian verb marr ("hold") and the Greek márē ("hand"), and also Greek márptō ("grab").

A common Balkan Indo-European root *aiğ(i)- ("goat") can be reflected in Albanian edh ("goat, kid") < PAlb *aidza and dhi ("nanny goat) < PAlb *aidzijɑ̄ with Greek αἴξ ("goat", gen. αἰγός) and Armenian ayc ("(nanny) goat"). It has been noted that the Balkan IE root and all the alleged Balto-Slavic and Indo-Iranian roots with a meaning "goat" are likely to be not Proto-Indo-European, as they may all originate as independent and relatively early, post-PIE borrowings, from the substrate languages spoken by the sedentary farmers who were encountered by immigrating Indo-European pastoralists. The view of a substrate borrowing can be corroborated by areal words for "goat" in other IE languages, such as Gothic gaits ("goat") and Latin haedus ("kid"), reflecting *gʰaid̯(-o)-, considered as a substrate word usually linked with Semitic languages (cf. Akkadian gadû, Aramaic gaδiā ̄"kid"). However it was most likely not directly borrowed from Semitic, but from a European substrate language that in turn had loaned the word from a common third source. Hence it can be viewed as an old cultural word, which was slowly transmitted to different European languages, and then adopted by the newcoming Indo-European speakers. Within this scenario it should be remarked the exclusive sharing of a common proto-form between Albanian, Greek, and Armenian, which could have been borrowed at a pre-stage that was common to these languages.

Shortly after they had diverged from one another, Albanian, Greek, and Armenian, undoubtedly also underwent a longer period of contact (as can be seen, for example, in the irregular correspondence: Greek σκόρ(ο)δον, Armenian sxtor, xstor, and Albanian hudhër, hurdhë "garlic"). Furthermore, intense Greek–Albanian contacts certainly have occurred thereafter. An example of secondary derivations from Palaeo-Balkan linguistic contacts is the Thracian word σπίνος spínos 'a kind of stone, which blazes when water touches it' (i.e. 'lime'), attested in Aristotle and Theophrastus, with cognate Greek τίτανος (Attic) and κίττανος (Doric) 'gypsum, chalk, lime', stemming PIE *k̑witn̥Hos 'white, whitish': although from the same PIE root, Albanian shpâ(ni) 'lime, tartar' and Greek σπίνος 'lime' derive from a secondary origin as they were probably borrowed from Thracian due to phonetic reasons. Indeed, the original IE cluster *k̑w- yields Albanian s- before any vowel, while in Thracian it could yield sp-.

Specifically Indo-Iranian/Greek/Albanian and Greek/Armenian/Albanian isoglosses are both relatively rare, examples including ndaj (to divide; Indo-Greek-Albanian) and ëndërr ("dream"; Greek/Armenian/Albanian). Armenian/Albanian isoglosses are considered "insignificant" by Orel. There are a considerable number of Indo-Iranian/Albanian isoglosses, which are notably often connected with horses, horse tending, and milk products.

In older literature, Orel (2000) argues that Albanian has a large number of isoglosses that are common to Albanian, Germanic, Baltic and Slavic, as part of a "North Eastern" lexical grouping, with a large number of these referring to wood or objects made out of wood. Orel (1998) noted 24 isoglosses between Balto-Slavic and Albanian, 48 common words between Baltic and Albanian and 24 between Albanian and Slavic. Hyllested & Joseph (2022) review Orel's common items and argue that a substantial number don't have convincing etymologies or do not constitute isoglosses between Balto-Slavic and Albanian. An example is Albanian murg (dark) and Lithuanian margas (colourful) which Orel considers to be isoglosses but both are equally related to Proto-Germanic *murkaz, ancient Greek ἀμορβός amorbos and Proto-Slavic *mergъ.

Orel identifies only one Albanian/Italic/Celtic isogloss, blertë ("green"), cognate to Latin flōrus ("bright") and Irish blár ("gray"). Specifically Celtic/Albanian vocabulary was previously thought to be limited although including at least one core vocabulary item (hënë "moon", cognate to Welsh cann "white" and Breton cann "full moon"), but recent work by Trumper in 2018 has proposed a larger though still not overwhelming set, with the notable addition of dritë ("light").

Although knowledge of Tocharian is fragmentary, the one known Albanian/Tocharian isogloss is "very important" as noted by Orel: kush ("who", cognate to Tocharian A kus, with the same meaning).