Vasavadatta was the princess of Ujjain, she was married with Udayana was the son of king Sahasranika of Vatsa kingdom.
Two Sanskrit plays of Bhasa deal with Vasavadatta and Udayana.
Pratijnayaugandharayana – The Pledge of Minister Yaugandharayana
Svapnavasavadattam – The dream of Vasavadatta.
Read about Udayana and Vasavadatta here