Muslim scientists were brought to work on calendar making and astronomy. Kublai Khan brought Iranians to Beijing to construct an observatory and an institution for astronomical studies.[12] Jamal ad-Din, a Persian astronomer, presented Kublai Khan with seven Persian astronomical instruments.[13] The work of Islamic geographers also reached China during the Yuan dynasty and was later used in the Ming dynasty to draw the Western Regions in the Da Ming Hun Yi Tu, the oldest surviving world map from East Asia.