Kingdom of Kannauj

The Kingdom of Kannauj was a kingdom in Northern India during the Early Mediaeval Era. It was established by Harivarman in 510 who was crowned Maharaja of Kannauj by the Magadhan Emperor. The kingdom of Kannauj expanded into a vast realm that spanned across northern India during the reign of Harshavardhana in the early seventh century.

Kannauj became the most important city in North India during this period, and hence was contested by the three great powers of the subcontinent of the period — the Gurjara Empire under the Pratihara dynasty, the Bengal Empire under the Pala dynasty, and the Rashtrakutas of Manyakheta. The prestige of Kannauj sowly dwindled after the war and Delhi became the most important city of North India.

Maukhari dynasty
In 510, the Narsimhagupta, the Emperor of Magadha, crowned Harivarman as the Maharaja of Kannauj, creating a vassal state in the region and the House of Maukhari. His great-grandson, Ishanavarman, declared independence from Magadha and proclaimed himself Maharajadhiraja of Kannauj. He defeated the kings of Gauda, Sulika and Andhra. The Emperor of Magadha, Kumargupta III defeated Ishanavarman but couldn't conquer Kannauj. His grandson, Grahavarman (r. 600–605) married Rajyashri, daughter of Prabhakarvardhana, King of Thanesar. Both the kings were killed in a war with Malavas and the Kingdom of Gauda, following which Harsha, the son of dead king of Thanesar, vowed to avenge the death of his father and brother-in-law and rescue his sister.

Pushyabhuti dynasty
Harshavarshana ascended the throne of Thanesar in 606 at the age of 16. He defeated and killed the king of Gauda and rescued his widowed sister. He was then crowned the Emperor of Kannauj by the representatives of multiple principalities and kingdoms of North India in a grand ceremony at Kannauj. He reigned until 647.

Arunasva
Harsha's rule was succeeded by that of Arunasva. Since Harsha had no heir, Arunasva usurped the throne. Arunavasa is known to have repelled the invasion by the Arab Rashidun Caliphate.

Varman dynasty
Arunavasa was succeeded by the rule of Yashovarman who established the Varman dynasty. Yashovarman led military campaigns in Bengal, Indus Valley, the Deccan and Kashmir. He was succeeded by Ama, Dunduka and Bhoja who were weak rulers.

Ayudha dynasty
In 770, Bhoja was deposed by Vajrayudha founding the Ayudha dynasty. This triggered Kannauj Wars (770–854) for the control over the Kingdom of Kannauj between three great powers — the Gurjara Empire under the Rajput Pratihara dynasty, the Bengal Empire under the House of Pala, and the Rashtrakuta Empire. In 785, Vatsaraja, the Gurjara Emperor invaded Kannauj, made Indrayudha, the King of Kannuj his vassal. In response to this, Dharmapala, the Emperor of Bengal invaded Kannauj and deposed Indrayudha and replaced him with Indrayudha's brother, Chakrayudha whom he made his vassal at an imperial court at Kannauj attended by the rulers of Bhoja (possibly Vidarbha), Matsya (Jaipur and north-east Rajasthan), Madra (East Punjab), Kuru (Haryana-Delhi-Western UP region), Yadu (possibly Mathura, Dwarka or Siṁhapura in the Punjab (Katas Raj Temples)), Yavana, Avanti, Gandhara and Kira (Kangra Valley). This obviously led to war and the Gurjara Empire defeated Bengal and the Gurjara Emperor Vatsaraja occupied Kannauj. Rashtrakuta Emperor Dhruva defeated the Gurjara Empire and Vatsaraja fled his empire, while Dhruva returned to his empire. Bengal re-installed Chakrayudha as the King of Kannauj and its vassal.

After the death of Dhruva in 793, the Rashtrakuta Empire fell into a war of succession. In the Gurjara Empire, the son of Vatsaraja, Nagabhata II, seeking revenge and taking advantage of the succession crisis in the Rashtrakuta Empire, invaded Kannauj and defeated Dharmapala and made Chakrayudha his vassal. Before he could invade Bengal however, the new Rashtrakuta Emperor Govinda III invaded Kannauj and defeated the Gurjara armies, and Nagabhatta retreated back to his empire. Dharmapala and Chakrayudha acknowledged Govinda III as their overlords to earn his friendship after which Govinda went back and Kannauj came back under Bengal rule in 800. Kannauj remained a vassal of the Bengal Empire until 816 when the Gurjara Emperor Nagabhata II invaded the Kingdom of Kannauj and conquered it and made the city of Kannauj its capital.

Territorial extent
The Kingdom of Kannauj dominated the upper Gangetic basin and parts of middle Gangetic basin during its early stages. Following the coronation of Harshavardhan, the Kingdom of Thanesar, i.e., eastern Punjab and the Trans-Gangetic Plain was merged into the Kingdom of Kannauj. Harshavardhan's campaigns expanded the empire of Kannauj to include the entirety of the Gangetic plain and eastern Punjab, as well as the Bundelkhand and Malwa.

Under the Varmans, the Kingdom of Kannauj lost control over Malwa and later Bengal. Other territories were lost during the Kannauj Wars, and significant power and territory was lost as the kingdom transitioned into a vassal state in turn under Bengal and Gurjaratra.