At the same time, during the Mongol invasions of Vietnam, several Mongol generals were Muslims, including Omar Nasr al-Din, and the major bulk of Mongol army invading Đại Việt and Champa came from the Turks and Persians. During their short conquest, the Mongols managed to spread Islam, although it was never large enough to challenge the Vietnamese. The first solid evidence of a Muslim presence in northern Vietnam dated to 1274, when two Muslim refugees fled from China to Đại Việt during the Mongol conquest of China. During a visit to Champa in 1340s, Ibn Battuta described a princess who met him, spoke in Turkish, was literate in Arabic, and wrote out the bismillah in the presence of the visitor. However, Ibn Battuta did not consider Champa an Islamic state. The number of followers began to increase as contacts with Sultanate of Malacca broadened in the wake of the 1471 collapse of the Champa Kingdom, but Islam would not become widespread among the Cham until the mid-17th century.