Meanwhile, Uriyangkhadai's forces invaded Vietnam with generals Trechecdu and Aju and captured the Trần dynasty capital of Thang Long in 1258. While Chinese source material incorrectly stated that Uriyangkhadai withdrew from Vietnam after nine days due to poor climate, his forces did not leave until 1259. In 1259, Uriyangkhadai's forces attacked Guangxi from Thang Long as part of a coordinated Mongol attack in 1259 with armies attacking in Sichuan under Mongol leader Möngke Khan and other Mongol armies attacking in modern-day Shandong and Henan. Möngke Khan died during the Siege of Diaoyu Castle while attacking the Sichuan anti-Mongol fortresses in Chongqing on August 11, 1259. There are several different claims as to how he died; the causes of death include either an arrow wound from a Chinese archer during the siege, dysentery, or cholera epidemic.