Vajji was a mahajanapada towards the north of Ganga in the division of Tirhut. It was a confederacy of eight or nine clans. The capital of Vajji mahajanapada was situated at Vaishali.
Towards the end of the reign of Rajadhiraja Chola, he sacked the Western Chalukyan capital Kalyanapuram and assumed the title Kalyanapuramgonda Chola and performed a Virabhisheka under the name Vijaya Rajendra Cholan.