Banu Bakr
Ibn Athīr is the family name of three brothers, all famous in Arabic literature, born at Jazīrat ibn Umar (today's "Cizre" nowadays in south-eastern Turkey) in upper Mesopotamia. The ibn al-Athir brothers belonged to the Shayban lineage of the large and influential Arab tribe Banu Bakr, who lived across upper Mesopotamia, and gave their name to the city of Diyar Bakr.