Mongolia is a huge but thinly-populated country between China and Russia. Vajrayana Buddhism was introduced into Mongolia from Tibet after the 15th century and in time the whole population became Buddhist.
In the early 1920’s, the country’s government became communist and during the next decade all temples and monasteries were closed and all monks were either murdered, imprisoned or fled into exile. It was only with the reintroduction of democracy in 1990 that Mongolians were free again to practice their religion. Today a majority (94%) of Mongolians still call themselves Buddhists, but the Sangha has been slow to recover from decades of persecution and a deep knowledge of the Dhamma by the people is not common.
The Religions of Mongolia, W.Heissig, 1979.