The Tripartite struggle was a struggle for power and control over the central Gangetic valley among three major empires in India during the 8th Century. These three empires were the Pratiharas, the Rastrakutas and the Palas. The Pratiharas were settled in western India in the Avanti - Jalaor region. The Rastrakutas who were essentially from the Deccan region were interested in Kannauj due to the fact that it formed an important center for trade and commerce. The Palas occupied the eastern parts of India (present day Bengal) and were very strong contenders in this struggle.
The Pratihara ruler named Vatsaraja had a dire ambition to take control
over the region of Kannauj. At the same time, the Pala ruler Dharmapala
also had an eye over the same region. This brought the two rulers into a
conflict. During this time the Rastrakuta king Dhruva attacked the two
of them and claimed to have won. This is what led to the Tripartite
Struggle. Dharmapala however somehow gained control over the territory
and set his nominee on the throne. The Rastrakutas were busy with their
own problems in their kingdom in south.
During the end of the 8th Century, the successor of Pratihara ruler
Vatsaraja named Nagabhata II attacked Kannauj and established his rule,
though it was short lived. In the beginning of the 9th Century he was
defeated by the Rastrakuta ruler Govinda III. However, he was kept busy
in internal politics by an alliance of different kingdoms in the south.
The struggle for Kannauj became serious after the Pratiharas exercised
control over it.
During the rule of Krishna III, there was successful campaign against
the Cholas. The Rastrakutas also formed a matrimonial relationship with
the Gangas and defeated the kingdom of Vengi. By the end of the 9th
Century the power of the Rastrakutas started to decline along with the
Palas. This was seen as an ideal opportunity by the feudal king Taila II
who defeated the Rastrakuta ruler and declared his kingdom there. This
came to be known the Later Chalukya dynasty. Their kingdom included the
states of Karnataka, Konkan and northern Godavari. By the end of the
tripartite struggle, the Pratiharas emerged victorious and established
themselves as the rulers of central India.