sentences:  In the 4th century AD, the Tanukhids formed a major grouping of Rome's allies in the East, ranging from Syria in the north to the Gulf of Aqaba, areas into which they had migrated from southern Arabia after the rise of Sassanian influence in Yemen a century earlier.They are reported to have been devoted to Christianity, Thomas the Apostle and monasticism, with many monasteries associated with the tribe.The Tanukhids played a key role in the defeat of Zenobia's forces by Emperor Aurelian and served as "foederati" in the Roman East - the first Arab tribe to do so.