A zhuz (Kazakh: жүз jüz ء جۇز [ʒʉz], also translated as "horde" or "hundred") is one of the three main territorial and tribal divisions in the Kypchak Plain area that covers much of the contemporary Kazakhstan, and represents the main tribal division within the ethnic group of the Kazakhs.
The earliest mention of the Kazakh jüz or hordes dates to the 17th century. Velyaminov-Zernov (1919) believed that the division arose as a result of the capture of the important cities of Tashkent, Yasi, and Sayram in 1598.
Some researchers argued that the jüz in origin corresponded to tribal, military alliances of steppe nomads that emerged around mid-16th century after the disintegration of the Kazakh Khanate. Yuri Zuev argued their territorial division comprises three ecological or topographic zones, the Senior zhuz of the southern and southeastern steppe being set apart from the two other zones by Lake Balkhash.
According to Kazakh legends, the three jüz were the territorial inheritances of the three sons of the mythical founder father of the Kazakhs. In Kazakh language, jüz means either "union" or "hundred".
Historically, the Senior zhuz (Kazakh: Ұлы жүз, Ulı jüz, ۇلى ء جۇز; Russian: Старший жуз, Staršij žuz) inhabited the northern lands of the former Chagatai Ulus of the Mongol Empire, in the Ili River and Chu River basins, in today's South-Eastern Kazakhstan and China's Ili Kazakh Autonomous Prefecture (northern Xinjiang). It was also called Üysin jüz.