At the end of 10th century and the beginning of the 11th century, the Kimak state collapsed. One of the reasons was the confrontation between Kypchak tribes that were under the power of the Kimak Kagan. Kipchaks insurrected against the central government and established a hegemony over the territory from the Irtysh River to the Volga.

The second reason of the fall of the Kimak state was the intensification of internal feuds of the Khanate.
An equally important factor of the fall of the Kimak Khanate was migratory flows occurring due to the formation of the Khitan state in northern China in 916. Expansion of the land to the west of this empire eventually resulted in the movement of nomadic tribes. The echoes of the grand migration of tribes appeared in many medieval sources: Arab-Persian, Russian, Armenian, Hungarian, Byzantine, and Syrian documents.
Arab scholar al-Marvazi (12th century) preserved some information regarding this movement. «Among them (the Turks), there is a group of people who are called Kuns. They came from the land of China, fearing the Chinese Hagan. They are Nestorian Christians. They left their territories because of the narrowness of pastures. Among them is Ikinji ibn Kochkar the Horezmian shah. They (the Kuns) were pursued by the people called Kai. They are much more numerous and stronger than them. They drove them to those pastures. Kuns then moved on to the land of Shars, and the Shars moved to the land of Turkmens. Turkmens moved to the eastern lands of Oguzes and Ozuzes moved to the land of Pechenegs, near the Armenian Sea» [1]. The Armenian Sea meant the Black Sea. Therefore, this migration affected people from China to the Black Sea.

Kais and Kuns, who left their land, hit the Kimaks, who were weakened in the North-East Seven Rivers Region and the Irtysh. Thus, Kais forced Kipchaks to move displacing Oguzes from the Syr Darya Basin, Western Aral and the Northern Caspian. They forced them to move to the southern Russian and Black Sea steppes.

After the capturing the Oguz lands, Kipchak Khans became significantly stronger and became first in strength and power on the main territory of the former settlement of Kimek-Kipchak and Kumanian tribes. During these events, Kimeks not only lost political hegemony, but also became dependent on Kipchaks. A part of Kimeks managed to stay in the Irtysh regions, another second part of them was in Turkestan and Central Asia, and a third group being part of Kipchak tribes moved west and to the southern Russian steppes.
The successors of Kimeks were Kypchaks [2].

1. Minorsky v. Sharafal-Zaman Tahir Marvazi on China, the Turks and India. Arabic text with an English translation and commentary. London, 1942, p. 18.

2. B. E. Kumekov. Arabic Sources on History of Kypchaks, Kumans and Kamaks 8–13 centuries. S-Pt, 1994, p. 19.