The Oghuz, Oguz or Ghuzz Turks were a western Turkic people who spoke the Oghuz languages from the Common branch of Turkic language family. In the 8th century, they formed a tribal confederation conventionally named the Oghuz Yabgu State in central Asia. The name Oghuz is a Common Turkic word for "tribe". Byzantine sources call the Oghuz the Uzes (Οὐ̑ζοι, Ouzoi). By the 10th century, Islamic sources were calling the Muslim, as opposed to shamanist or Christian, Oghuz the Turkmens. By the 12th century this term had passed into Byzantine usage and the Oghuzes were overwhelmingly Muslim.
The Oghuz confederation migrated westward from the Jeti-su area after a conflict with the Karluk branch of Uigurs. The founders of the Ottoman Empire were descendants of the Oghuzes. Today the residents of Turkey, Turkmenistan, Azerbaijan, Khorezm, Turkmens of Afghanistan, Balkans, Iraq and Syria are descendants of Oghuz Turks and their language belongs to the Oghuz (a.k.a. southwestern Turkic) group of the Turkic languages family.
In the 9th century, the Oghuzes from the Aral steppes drove Bechens from the Emba and Ural River region toward the west. In the 10th century, they inhabited the steppe of the rivers Sari-su, Turgai, and Emba to the north of Lake Balkhash of modern-day Kazakhstan. A clan of this nation, the Seljuks, embraced Islam and in the 11th century entered Persia, where they founded the Great Seljuk Empire. Similarly in the 11th century, a Tengriist Oghuz clan—referred to as Uzes or Torks in the Russian chronicles—overthrew Pecheneg supremacy in the Russian steppe. Harried by another Turkic people, the Kipchaks, these Oghuz penetrated as far as the lower Danube, crossed it and invaded the Balkans, where they were either crushed or struck down by an outbreak of plague, causing the survivors either to flee or to join the Byzantine imperial forces as mercenaries (1065).