In the 4th century, it became a pilgrimage town for Christians coming to venerate Saint Sergius, a Christian Roman soldier said to have been martyred in Resafa during the Diocletianic Persecution. A church was built to mark his grave, and the city was renamed Sergiopolis. Indeed, it became, after Jerusalem, "most important pilgrimage center in Byzantine Oriens in proto-Byzantine period", with a special appeal to the local Arabs, especially the Ghassanids. By the late 6th century, the Ghassanids’ tribal Arab ally the Bahra’ were tasked with guarding Resafa and its shrine from nomadic marauders and the Lakhmids of Mesopotamia.