 Because the Han Chinese commander Guo Kan fought with the Mongols under Hulagu in the Middle East, Kublai had heard of siege engines of great effectiveness.Experts Ismail and Al al-Din were sent by Abagha, Ilkhan of Persia, to China by the decree of Kublai Khan in 1272.They built the powerful mangonels under the Uyghur general Arikhgiya by March, 1273.