In the 15th century, Mongolia was split into two groups called the Oirad and the Khalkha and for a short period the Oirad, under the rule of Dayan Khan, reunited Mongolia. In the 16th century, the Mongols came to rule a considerable part of Asia and even defeated the Khalkhas. After his death, Mongolia once again split into waring groups but was again brought together by Altan Khan. Under his rule, they continued to invade China but in 1571 they signed a treaty with the Chinese Ming Dynasty. Next he invaded Tibet, converted to Buddhism and named the first Dalai Lama.

In the 17th century, Mongolia lost much of its power as they moved into Russian lands and were defeated in the mid-17th century. During this period, Buddhism became more popular until they formed a protectorate over Tibet. At the same time, the Chinese Qing dynasty took control and moved into Northern Mongolia. In 1911, this rule ended and for a short time, outer Mongolia established a theocracy. Eight years later, a Chinese warlord took control followed by a Russian warlord in 1920. Russian troops later defeated the Russian warlord and Mongolia became a Soviet satellite.