Oguzes were mostly pagans who worshiped shamans. However, Islam gradually penetrated into their environment. According to Mahmud Kashgari (9th century), Oguzes were divided into two large fraternities: Buzuks and Uchuks, comprised of 12 tribes. Buzuks enjoyed great advantages. In the 9th — 10th centuries, the Oguz state went through a process of disintegration of old tribal institutions with the development of patriarchal-feudal relations. At the beginning of the 12th century, the Oguz tribes adopted a system of tax collection. Khan’s special collectors had employees mounted on horses, numbering up to a thousand people. In case of refusal to pay a tribute, punitive squads were sent to the «rebels». Private property was developing. The difference was clearly manifested between the lowest rank (common people, the poor and slaves) and the higher levels of society.

Lack of cattle forced poor nomads to be more intensively engaged in agriculture and handicrafts. In the steppe and the settled agricultural zone, the slave trade was widespread. In the 9th century, the rulers of Khorasan sent to the court of the Caliph of Baghdad at least two thousand Oguz slaves every year.
This social imbalance led to the fact that at the turn of the 10th-11th centuries, the Oguz Jabgu was dissatisfied with the high level of taxes and rebelled against the actions of the state elite. The leaders of Seljuks, who settled near Jenda, back in the middle of the 10th century, used this discontent to their advantage. They led a revolt against the rulers of the Oguz Yangikent and conquered Jenda, but not for long. Apparently, they did not meet the expectations and lost the support of masses. Otherwise, it is difficult to explain why they were soon forced to leave the Jenda region [1].

All this led to the strengthening of Shahmalika, heir and successor of Ali Khan, who came to power in the middle or at the beginning of the second half of the 10th century [2]. Under his reign, the state is so strengthened that the Oguzes invaded Khorezm in 1041. However, two years later, Shahmalik, the last well-known Oguz, was executed by Seljuks.

After years of feuds and wars, the power of Jabgu, weakened by deep internal contradictions, finally fell being hit by Kipchak tribal chiefs. Under the pressure of the adversary, large groups of Oguzes left the territory of Eastern Europe and Asia Minor, the rest moved to Central Asia and Iran. The remaining Oguzes subsequently dissolved among the Turkic-speaking tribes of Desht-i-Kypshak.

Nevertheless, the Oguz heritage was not lost completely and the fables about famous Korkyt preserved by Kazakh is a proof of that.

1. History of Kazakhstan: from ancient times until today, in five volumes. — Almaty: Atamura, 2010. Volume 1. 544 pp. — P. 318.
2. S. G. Agajanov. History essays of Oguzes and Turkmens, pp. 151 — 153.