Throughout the 6th century, the Tayy continued their relations with the Sassanids and their chief Arab clients, the Lakhmids of Mesopotamia. Towards the end of the 6th century, a Tayyid chief named Hassan assisted the Sassanid king Khosrow II when the latter fled from his usurper, Bahram Chobin, by giving Khosrow a horse. A few years later, the Lakhmid governor of al-Hirah, al-Nu'man III fell out with Khosrow II, who had been restored to the Sassanid throne, and sought safety with the Tayy. The tribe refused to grant refuge to al-Nu'man, who was married to two Tayyid women, and he was ultimately killed by the Sassanids in 602. A Tayyid chief, Iyas ibn Qabisah al-Ta'i, subsequently migrated to al-Hirah with some of his tribesmen and became its governor, ruling from 602 to 611 CE. The Banu Bakr ibn Wa'il tribe opposed the rule of Iyas and began raiding Sassanid territory in southern Mesopotamia. In response, Iyas commanded pro-Sassanid Arab and Persian troops against the Banu Bakr at the Battle of Dhi Qar in 609, in which the Sassanids were defeated.