The article deals with the history of the Arab tribal confederation of Banū Iyād in the pre-Islamic times. Banū Iyād were a branch of the Northern Arabs aka Banū ‛Adnān. Their original dwelling places were in Tihāma, in the west of Arabia. Thence Banū Iyād migrated to different parts of Arabia and beyond. A number of their migrations can be traced according to the extant sources. Some of Banū Iyād went to Yemen, settled near the Madhij tribe (belonging to the Banū Qaḥṭān, or Southern Arabs) and merged with the latter. Those Banū Iyād are probably referred to in the South Arabian ‛Abadān 1 inscription. Other Banū Iyād remained in Tihāma. They were chased thence by the confederations of Banū Rabī‘a and Banū Muḍar, whereupon they migrated to the east of Arabia. There were three migrations of Banū Iyād to the east of Arabia and to Iraq. Some tribes went to the south of Iraq together with the Tanūkh tribal confederation from the Bahrain region (extending then from Basra to Oman) in the beginning of the third century at the latest. Others migrated approximately in the middle of that century, but without staying in the Bahrain region. The third migration, again from the Bahrain region, occurred in the beginning of the fourth century, when Banū Iyād were pressed by Banū Rabī‘a tribes. Banū Iyād settled in different places, including near ‘Ayn Ubāgh on the Euphrates and on the wādī Sindād between al-Ḥīra and al-Ubulla. The Banū Iyād who lived on the wādī Sindād probably arrived in Iraq in the course of their third migration. They appear to have been under the suzerainty of the Persian Sasanids but they considered themselves independent. In the first half of the sixth century, Banū Iyād started raiding the Sasanid possessions in southern Iraq. This brought about a war. Banū Iyād were defeated. The Sasanids settled them in northern Iraq whereupon Banū Iyād migrated to Byzantine Syria. Those Banuˉ Iyāol who arrived in Irak with the Tanukh were subjects of the rulers of al-Ḥīra.