Abtai Sain Khan

Abtai was born in 1554 to the Khalkha Mongol prince Onokhui üizen Noyan (b. 1534). He was the eldest among Onokhui üizen Noyan's five sons which include Abugho, Tarni, Tumengken, and Barai. He was the great-grandson of Dayan Khan(1464–1517) and grandson of Gersenji Khuntaij(1513–1549). Blood smeared on his fingers at birth presaged a great warrior and from 1567 to 1580 Abtai led several campaigns against western Oirat Mongol tribes, finally defeating the Oirats' Khoshut tribe at Köbkör Keriye in the mid-1580s. Abtai then placed his son Shubuudai on the Oirat throne.

Around 1580, Abtai learned that his uncle Altan Khan (1507–1583) of the Tumeds had converted to Gelupga (Yellow Hat) Tibetan Buddhism. Abtai invited the lama Shiregetü Güüshi Chorjiwa from Altan's Inner Mongolian city Guihua (present day Hohhot) to teach him the basic tenets of Tibetan Buddhism.

In pre-revolutionary Mongolia a special cult devoted to Abtai Khan flourished. He was celebrated as the last ruler who tried to unite Mongolia after the collapse of the Yuan Dynasty and who introduced Buddhism to Mongolia.