Arabs in 710. Medieval history (710–1506) Arab Caliphate (710–867) The Transoxiana principalities never formed a viable confederacy. Beginning in 651, the Arabs organized periodic marauding raids deep into the territory of Transoxania, but it was not until the appointment of Ibn Qutaiba as Governor of Khorasan in 705, during the reign of Walid I, that the Caliphate adopted the policy of annexing the lands beyond the Oxus. In 715, the task of annexation was accomplished. The entire region thus came under the control of the Caliph and of Islam, but the Arabs continued to rule through local Soghdian Kings and dihqans. The ascension of the Abbasids to rule the Caliphate (750 - 1258) opened a new era in the history of Central Asia. While their predecessors the Umayyads (661 - 750) were little more than leaders of a loose confederation of Arab tribes, the Abbasids set out to build a huge multi-ethnic centralized state that would emulate and perfect the Sassanian government machine. They gave the Near East and Transoxiana a unity, which they had been lacking since the time of Alexander the Great. Samanid Empire (819–999) The Samanid dynasty ruled (819–1005) in Khorasan (including Eastern Iran and Transoxiana) and was founded by Saman Khuda. The Samanids were one of the first purely indigenous dynasties to rule in Persia after the Muslim Arab conquest. During the reign (892–907) of Saman Khuda's great-grandson, Ismail I (known as Ismail Samani), Samanids expanded in Khorasan. In 900, Ismail defeated the Saffarids in Khorasan (area of current Northwest Afghanistan and northeastern Iran), while his brother was the governor of Transoxiana. Thus, Samanid rule was acclaimed over the combined regions. The cities of Bukhara (the Samanid capital) and Samarkand became centres of art, science, and literature; industries included pottery making and bronze casting. After 950, Samanid power weakened, but was briefly revitalized under Nuh II, who ruled from 976 to 997. However, with the oncoming encroachment of Muslim Turks, the Samanids lost their domains south of the Oxus river which were taken by Ghaznavids. In 999, Bukhara was taken by the Qarakhanids. The Samanid Isma'il Muntasir (died 1005) tried to restore the dynasty (1000–1005), until he was assassinated by an Arab bedouin chieftain. The attack of the Qarakhanid Turks ended the Samanid dynasty in 999 and dominance in Transoxiana passed on to Turkic rulers. Qarakhanids (999–1211) and Khwarezmshahs (1211–1218) After the collapse of Samanid Dynasty,