The Ghassnid king al-Harith ibn Jabalah (reigned 529-569) supported the Byzantines against Sasanian Persia and was given the title patricius in 529 by the emperor Justinian. Al-Harith was a Monophysite Christian; he helped to revive the Syrian Monophysite Church and supported Monophysite development despite the disapproval of Orthodox Byzantium. Subsequent Byzantine distrust of such religious unorthodoxy brought down his successors, al-Mundhir (reigned 569-582) and Nu'man.
The Ghassanids, who had successfully opposed the Persian-oriented Lakhmids of al-Hirah, prospered economically and engaged in much religious and public building; they also patronized the arts and at one time entertained the poets Nabighah adh-Dhubyani and Hassan ibn Thabit at their courts. Ghassan remained a Byzantine vassal state until its rulers were overthrown by the Muslims in the 7th century.