The Mongol conquest of China began in 1205 with the gradual conquest of Western Xia by Genghis Khan, who also invaded Jin territories. In 1271, the Mongol leader Kublai Khan established the Yuan dynasty, which conquered the last remnant of the Song dynasty in 1279. Before the Mongol invasion, the population of Song China was 120 million citizens; this was reduced to 60 million by the time of the census in 1300. A peasant named Zhu Yuanzhang led a rebellion that overthrew the Yuan in 1368 and founded the Ming dynasty as the Hongwu Emperor. Under the Ming dynasty, China enjoyed another golden age, developing one of the strongest navies in the world and a rich and prosperous economy amid a flourishing of art and culture. It was during this period that admiral Zheng He led the Ming treasure voyages throughout the Indian Ocean, reaching as far as East Africa.