The Naiman (Mongolian: Найман, Naiman, "eight"; ; Kazakh: Найман, Naiman; Uzbek: Nayman) were a medieval tribe originating in the territory of modern Western Mongolia (possibly during the time of the Uyghur Khaganate), and are one of the tribes of modern Mongols and in the middle juz of the Kazakh nation. In The Secret History of the Mongols, the Naiman subtribe the "Güchügüd" are mentioned. According to Russian Turkologist Nikolai Aristov's view, the Naiman Khanate's western border reached the Irtysh River and its eastern border reached the Mongolian Tamir River. The Altai Mountains and southern Altai Republic were part of the Naiman Khanate. They had diplomatic relations with the Kara-Khitans, and were subservient to them until 1175. In the Russian and Soviet historiography of Central Asia they were traditionally ranked among the Mongol-speaking tribes. For instance, such Russian orientalists as Vasily Bartold, Grigory Potanin, Boris Vladimirtsov, Ilya Petrushevsky, Nicholas Poppe, Lev Gumilyov, Vadim Trepavlov classified them as one of mongol tribes. Other scholars classified them as a Turkic people from Sekiz Oghuz (means "Eight Oghuz" in Turkic). However, the term "Naiman" has Mongolian origin meaning "eight", but their titles are Turkic, and they are thought by some to be possibly Mongolized Turks. They have been described as Turkic-speaking, as well as Mongolian-speaking. Like the Khitans and the Uyghurs, many of them were Nestorian Christians or Buddhists. The Naimans were located to the west of the Mongols, and there were more Naimans than Mongols in the late 12th century. In 1199, Temüjin (Genghis Khan) together with an ally Ong khan launched a campaign against the Naimans. They defeat Buyirugh, a Naiman khan who ruled the mountain lineage. In 1203, the last Tayang khan, the ruler of Naimans of the steppe, was killed after a battle with Genghis Khan. His son Kuchlug with his remaining Naiman troops then fled to the Kara-Khitan Khanate. Kuchlug was well received there and the Khitan Khan gave him his daughter in marriage.