The Erdene Zuu Monastery is probably the earliest surviving Buddhist monastery in Mongolia. Located in Övörkhangai Province, approximately 2 km north-east from the center of Kharkhorin and adjacent to the ancient city of Karakorum, it is part of the Orkhon Valley Cultural Landscape World Heritage Site. Abtai Sain Khan, ruler of the Khalkha Mongols and grandfather of Zanabazar, the first Jebtsundamba Khutuktu, ordered construction of the Erdene Zuu monastery in 1585 after his meeting with the 3rd Dalai Lama and the declaration of Tibetan Buddhism as the state religion of Mongolia.