The Mongol invasion of Tibet can refer to the following campaigns by the Mongols against Tibet. The earliest is the alleged plot to invade Tibet by Genghis Khan in 1206, which is considered anachronistic; there is no evidence of Mongol-Tibetan encounters prior to the military campaign in 1240. The first confirmed campaign is the invasion of Tibet by the Mongol general Doorda Darkhan in 1240, a campaign of 30,000 troops that resulted in 500 casualties. The campaign was smaller than the full-scale invasions used by the Mongols against large empires. The purpose of this attack is unclear, and is still in debate among Tibetologists. Eventually Tibet capitulated to the Mongols, whose administrative rule over this region lasted until the mid-14th century, when the Yuan dynasty began to crumble.