 Complete the following phrase:  Since new Vietnamese king Lý Huệ Tông had ascended the throne in 1206, there were no tributary missions from Vietnam to China until the Trần clan took the throne of Lý family in 1225. In 1229, new Vietnamese ruler Trần Thái Tông sent a diplomatic mission to Song China, and he was recognized as king of Annam. After the first 