Geographically and politically, in early Islamic times the Diyar Mudar was usually part of al-Jazira. In the mid-10th century, the region came under
Hamdanid control, and under
Sayf al-Dawla it was detached from the Jazira and the Hamdanids of
Mosul and subordinated to the northern Syria-based
Emirate of Aleppo. In the same period, the region came under attack by the resurgent
Byzantine Empire. After the loss of control of the Hamdanids, the Diyar Mudar and its cities came under the sway of the
Banu Numayr, with
Waththab ibn Ja'bar al-Numayri becoming autonomous governor of Harran by 1002, while Edessa was conquered by the
Byzantine Empire under
George Maniakes in 1032. Thereafter the region became divided into a mostly Christian-ruled northern portion, subject to
Armenian colonization, while the area from Harran to the Euphrates was dominated by Arab nomadic tribes.
Seljuk raids began in the 1060s and 1070s but they could not take the region. After the battle of Manzikert,
Philaretos Brachamios appointed
Thoros as governor of Edessa and the Diyar Mudar, but Thoros retreated after some time to Melitene (though he was reappointed again as governor by the Seljuks in 1094). By 1086, the Seljuk
sultan Malik-Shah I had unified the province under his control. The advent of the
Crusades re-established the division between a Christian north (the
County of Edessa) and a Muslim south, which lasted until the mid-12th century. The
Ayyubids gained control of the region under
Saladin, and kept it until the
Mongol invasion of the Levant in 1260. ==Sources==