Origins

The name of the tribe means 'servant of the [god] Qays'.^[1] It belonged to the tribal groups originally resident in the area of al-Arid in South Arabia and which migrated northwestward to an area extending north to Sudayr and south to al-Kharj. Later, in the Arab genealogical tradition, these tribes were called the Rabi'a,^[1] a branch of the northern Arab Ma'add confederation.

Campaigns of Shapur II

In pre-Islamic times, the Abd al-Qays frequently raided Iran.^[2] The Sasanian king Shapur II (r. 309–379) led an expedition against the Arabian tribes, during which he massacred most of the Abd al-Qays.^[2] Later, several Abd al-Qays tribesmen were relocated by Shapur to the Iranian province of Kirman.^[2]

Migrations into eastern Arabia

By the 5th century, the Abd al-Qays had shifted to nomadism, dwelling outside of the Tuwaiq escarpment in the southern Najd (central Arabia). In the 6th century, the tribe migrated northeastward the oases of al-Ahsa , Tarout Island and Qatif in eastern Arabia.^[1]

Islamic period

During the Arab conquest of Iran, considerable numbers of Abd al-Qays tribesmen entered southeastern, launching extensive raids in the region.^[2] Several groupings of Abd al-Qays settled near Tavvaz in the Iranian coastal mountains and Basra in lower Mesopotamia.^[2] In the early 8th century, 4,000 Abd al-Qays warriors formed part of the army of Qutayba ibn Muslim on his campaign into Khorasan.^[2]

The majority of the Baharna are descendants of the Banu Abd al-Qays, while some are from the tribes of Bakr ibn Wa'il and others. ^{[3] [4]}