governorship of Abu 'l Abbas 'Abdallah b. Tahir (r. 828–845), a list of districts (kuwar) of the region exists, including as far as Saghaniyan in the north and Kabul in the south. Other places listed are Tirmidh, Juzjan, Bamiyan, Rūb and Samanjan. Some Arab geographers used the name only for the southern part of Oxus valley. Balkh was also a part of Khorasan along with other areas through varying extensions of time. Per al-Tabari, Yazdegerd fled from Marw-al Rudh to Balkh during Ahnaf's conquest of Khorasan in 643. He fortified himself but was defeated by the Arabs and fled across the Oxus River. Yazdegerd proceeded to Soghd, whose ruler supplied him a large army. The Khaqan of Turks after assembling the troops from Ferghana, crossed the Oxus along with Yazdegerd and marched to Balkh. In 652, Ibn Amir sent al-Ahnaf to invade Tokharistan with 4,000 Arabs and 1,000 Iranian Muslims (evidently the Tamimis and asawira), probably because of assistance of its ruler to Yazdegerd's son Peroz. He approached Balkh after conquering Marw al-Rudh and fighting an inconclusive battle with a 30,000-strong force from Guzgan, Faryab and Talqan. After arriving at Balkh, he besieged the city, with its inhabitants offering a tribute of 400,000 or 700,000 dirhams. He deputed his cousin to collect the tribute and advanced to Khwarezm but returned to Balkh as winter approached. It was in Balkh in fall of 652 when the local people introduced his cousin Asid to gifting gold and silver to their governor during Mihrijan. Ziyad b. Abi Sufyan reorganised Basra and Kufa, excluding many from the diwan and inspiring him to settle 50,000 families in Khorasan. Both Baladhuri and Mad'aini agree upon the number, though the latter states each half were from Basra and Kufa. Al-'Ali disagrees, stating the Kufans were 10,000. Ghalib had been unsuccessful in his expedition, and Rabi b. Ziyad al-Harithi, who was appointed governor of Khorasan in 671, led the settlement expedition. He advanced to Balkh and made a peace treaty with the locals who had revolted after al-Ahnaf's earlier treaty. Qutayba ibn Muslim led the final conquest of Balkh. He was tasked with subduing the revolt in Lower Tokharistan. His army was assembled in the spring of 705 and marched through Marw al-Rudh and Talqan to Balkh. Per one version in Tarikh al-Tabari, the city was surrendered peacefully. Another version, probably to promote a Bahilite claim on the