Ongiin Khiid (also referred to as Ongi Monastery ruins) is located at the foot of Mount Saikhan Ovoo, near the village of Saikhan Ovoo Sum of Dundgobi province. This monastery was one of the largest and most respected monasteries of Mongolia before its destruction in 1939 by the communist authorities.
Today Ongi Monastery is an active small monastery, built on the ruins of a monastery complex that was formerly one of the largest monasteries in Mongolia

History of Ongi Temple
Ongi, was built in 1660 and consisted of two temple complexes on the North and South banks of the Ongi River. At its peak time, overall there were over 30 temples, 4 Buddhist universities, and over 1000 monks at a time. This 2 monastery complex was built to commemorate the first-ever visit of the Dalai Lama to Mongolia

During the 1930s, socialism with the huge influence of Russia spread throughout Mongolia. The communist system was all against Buddhism. So both complexes of Ongi Monastery were completely destroyed in 1939 during anti-religious Stalinist purges. About 200 monks were executed, and many surviving monks were imprisoned or forced to join the Communist-controlled army.  

Thanks to the democratization of Mongolia in 1990, three monks who had begun their Buddhist education in Ongiin Khiid sixty years earlier, decided to return there. These monks started laying the foundation on the old ruins, with the purpose to restore the Ongi monastery. At present, one temple has been fully rebuilt, with small museums and ruins of the temples. Around the Ongi monastery, there are some tourist camps. There is a bright yellow ger that displays some old objects that were used in its glorious period.