Erdene Zuu is regarded as the oldest surviving Buddhist monastery of Mongolia and was founded in 1585 by Abatai Khan, a descendant of Chinggis Khan. The area was formerly known as Kharkhorum, the palace and adminstrative center of the Mongol empire. Erdene Zuu was initially a Sakya institution but was converted to Geluk in 1685 during the time of the First Jetsundampa. Though severely damaged during the communist purges of the early 20th century, Erdene Zuu has been revitalized since 1990 and is an active site of Buddhist practice. The surrounding region was designated as a UNESCO world heritage site in 2004.