What was the Tripartite Struggle, and which dynasties were involved?

After Harṣha's death in 647 CE, north India saw political turmoil. Three powerful dynasties fought for control of Kannauj during the 8th and 9th centuries. These were the Pālas from the east, Gurjara-Pratīhāras from the west, and Rāṣhṭrakūṭas from the Deccan. Kannauj was important for its strategic location.