involved in capturing it. He divided the booty at his own discretion among the early Emigrants and two poor Helpers, Abu Dujana and Suhail bin Haneef. Other examples include the Invasion of Banu Qurayza in February–March 627 and the siege of Ta'if in January 630. Mongols and Chinese In the Middle Ages, the Mongol Empire's campaign against China (then comprising the Western Xia Dynasty, Jin Dynasty, and Southern Song dynasty) by Genghis Khan until Kublai Khan, who eventually established the Yuan Dynasty in 1271, was very effective, allowing the Mongols to sweep through large areas. Even if they could not enter some of the more well-fortified cities, they used innovative battle tactics to grab hold of the land and the people: By concentrating on the field armies, the strongholds had to wait. Of course, smaller fortresses, or ones easily surprised, were taken as they came along. This had two effects. First, it cut off the principal city from communicating with other cities where they might expect aid. Secondly, refugees from these smaller cities would flee to the last stronghold. The reports from these cities and the streaming hordes of refugees not only reduced the morale of the inhabitants and garrison of the principal city, it also strained their resources. Food and water reserves were taxed by the sudden influx of refugees. Soon, what was once a formidable undertaking became easy. The Mongols were then free to lay siege without interference of the field army, as it had been destroyed. At the siege of Aleppo, Hulagu used twenty catapults against the Bab al-Iraq (Gate of Iraq) alone. In Jûzjânî, there are several episodes in which the Mongols constructed hundreds of siege machines in order to surpass the number which the defending city possessed. While Jûzjânî surely exaggerated, the improbably high numbers which he used for both the Mongols and the defenders do give one a sense of the large numbers of machines used at a single siege. Another Mongol tactic was to use catapults to launch corpses of plague victims into besieged cities. The disease-carrying fleas from the bodies would then infest the city, and the plague would spread, allowing the city to be easily captured, although this transmission mechanism was not known at the time. In 1346, the bodies of Mongol warriors of the Golden Horde who had died of plague were thrown over the walls of the Crimean city