In the ninth century, the continued influx of nomads from the northern steppes brought a new group of people into Central Asia. These people were the Turks who lived in the great grasslands stretching from Mongolia to the Caspian Sea. Introduced mainly as slave soldiers to the Samanid Dynasty, these Turks served in the armies of all the states of the region, including the Abbasid army.

In the late tenth century, as the Samanids began to lose control of Mawarannahr and northeastern Iran, some of these soldiers came to positions of power in the government of the region, and eventually they established their own states. With the emergence of a Turkic ruling group in the region, other Turkic tribes began to migrate to Mawarannahr.

The first of the Turkic states in the region was the Ghaznavid Empire, established in the last years of the tenth century. The Ghaznavid state, which ruled lands south of the Amu Darya, was able to conquer large areas of Iran, Afghanistan, and northern India during the reign of Sultan Mahmud. The dominance of Ghazna was curtailed, however, when large-scale Turkic migrations brought in two new groups of Turks who undermined the Ghaznavids. In the east, these Turks were led by the Qarakhanids, who conquered the Samanids. Then the Seljuk family led Turks into the western part of the region, conquering the Ghaznavid territory of Khorazm (also spelled Khorezm and Khwarazm).

Attracted by the wealth of Central Asia as were earlier groups, the Seljuks dominated a wide area from Asia Minor to the western sections of Mawarannahr, in Afghanistan, Iran, and Iraq in the eleventh century. The Seljuk Empire then split into states ruled by various local Turkic and Iranian rulers. The culture and intellectual life of the region continued unaffected by such political changes, however. Turkic tribes from the north continued to migrate into the region during this period.

In the late twelfth century, a Turkic leader of Khorazm, which is the region south of the Aral Sea, united Khorazm, Mawarannahr, and Iran under his rule. Under the rule of the Khorazm shah Kutbeddin Muhammad and his son, Muhammad II, Mawarannahr continued to be prosperous and rich. However, a new incursion of nomads from the north soon changed this situation. This time the invader was Chinggis (Genghis) Khan with his Mongol armies.