Selencia

Selencia was an early 12th-century entity at or near the southern coast of the Baltic Sea, mentioned only in the chronicles of Gallus Anonymus, who listed it as one of three northern neighbors of Piast Poland around 1115 (the other ones being "Pomorania" and "Pruzia." It has been proposed that Selencia was a misspelling of Luticia, or that Selencia was a short-lived state centered on the Oder estuary, probably destroyed when in 1122 Boleslaw III Wrymouth of Poland defeated, according to the annals of Cracow, a "Zuetopolc dux Odrensis."

Gallus Anonymus
Selencia is mentioned twice in the first book of Gallus Anonymus' Gesta principum Polonorum (The Poles' princes' deeds), a chronicle composed in Piast Poland between 1112 and 1118 to glorify the Piast dynasty in general, and the contemporary Piast ruler Boleslaw III Wrymouth in particular. The first mention is written in the present tense, describing Boleslaw III Wrymouth's fight against his pagan neighbors at the Baltic Sea - Selencians, Pomeranians and Old Prussians, while the second mention refers to Boleslaw I Chrobry's fight against the same peoples. Gaethke, Hans-Otto: Kämpfe und Herrschaft Heinrichs von (Alt-) Lübeck und Lothars von Supplingenburg im Slawenland 1093/1106-1125, in: Zeitschrift des Vereins für Lübeckische Geschichte und Altertumskunde (ZVLGA), vol. 80 (2000), pp. 63-163, here pp. 138. First mention in Gallus Anonymus: Gesta principum Polonorum lib. I prehum (in MGH SS 9, p. 425): "Ad mare autem septemtrionale vel anphitrionale tres habet affines barbarorum gentilium ferocissimas nationes, Selenciam, Pomeranam u et Pruziam, contra quas regiones Polonorum dux assidue pugnat, ut eas ad fidem convertat; sed nec gladio praedicationis cor eorum a perfidia potuit revocari, nec w gladio iugulationis eorum penitus vipperalis progenies aboleri. Saepe tamen principes eorum a duce Poloniensi proelio superati, ad baptismum confugerunt; itemque collectis viribus fidem christianam ab negantes, contra christianos bellum denuo paraverunt." English translation per Güttner Sporzynski, Darius von: Poland and the Papacy Before the Second Crusade, in Balard, Michel (ed.): La papauté et les croisades. Actes du VIIe Congrès de la Society for the Study of the Crusades and the Latin East, Avignon 27-31 aout 2008 (Crusades subsidia, vol. 3), Farnham 2011, pp. 257-270, here p. 260: "On the Northern Sea, [Poland] has as neighbours three most savage nations of pagan barbarians, Selencia, Pomerania, and Prussia, and the duke of the Poles is constantly at war with these countries, fighting to convert them to the faith. But neither has the sword of preaching been able to sway their hearts from faithlessness, nor the sword at their throats wiped out this generation of vipers in its entirety. Yet often their leaders when defeated in battle by the Polish duke have taken refuge in baptism, only to deny the Christian faith when they recovered their strength and take up arms afresh against the Christians."  Second mention in Gallus Anonymus: Gesta principum Polonorum lib. I.6 (in MGH SS 9, p. 428): "Ipse namque Selenciam, Pomoraniam et Prusiam usque adeo vel in perfidia resistentes contrivit vel conversas in fide solidavit, quod ecclesias ibi multas et episcopos per apostolicum, ymmo apostolicus per eum ordinavit." English translation: "For when Selencia, Pomerania and Prussia stood firmly by their unfaithfulness, he beat them down. When they had converted, he strengthened the faith by establishing many churches and bishops in the name of the pope - actually, the pope established them through him."