This article discusses the emergence of Diyār Bakr as the northern subdivision of the Jazīra in the early Islamic period. It shows that this sub-province is a product of the 10th century CE and not, as has hitherto been assumed, of the conquest or Umayyad period. As a first step, the paper traces the appearance of the name Diyār Bakr in the Arabic sources to the mid-10th century. It then turns to the ʿAbbāsid geographical tradition and gives an overview of the various portrayals of the region of the Jazīran north up to al-Muqaddasī (d. after 990), who is the first to provide a rudimentary depiction of the Jazīran north as ‘Diyār Bakr’. The article then turns to the history of the Banū Shaybān of Bakr/Rabīʿa in the Jazīran north to offer a tentative explanation for the origin of the term and administrative district of Diyār Bakr. It concludes with a brief discussion of the need to re-evaluate the political and administrative history of the Jazīra before the 10th century.