The aboriginal Siberian Tatars consist of three large ethnic groups, each of which has further subdivisions. The Tomsk Tatars are composed of the Kalmaks, the Chats, and the Eushta. They live along the Tomi and Ob rivers in the Tomsk District, and, in part, in the Kemerovsk and Novosibirsk districts. Among the Barabinsk Tatars, scholars have recently distinguished the following subgroups: the Barabo-Turashi, the Terenino-Choi, and the Liubei-Tunusy. They are settled in the Barabinsk steppe and the Novosibirsk region. The most numerous group, the Tobolo-Irtysh, consists of the Tars, Kurdak-Sargatsk, Tobolsk, Tiumen, and Iaskolbin Tatars. They live in the basins of the Irtysh and Tobol rivers in the Omsk and Tyumensk districts of Russia.