 It also became the origin of the Ayutthaya Kingdom, as the first King of Ayutthaya, Ramathibodi, was prince of U Thong when the city was struck by an epidemic, prompting him to relocate east and found Ayutthaya.U Thong District was created with the name "Chorakhe Sam Phan" in 1905.In 1939 the district was renamed U Thong.