Toward the declining Lý monarch's power in the late 12th century, the Trần clan from Nam Định eventually rise to power.^[154] In 1224, powerful court minister Trần Thủ Độ forced the emperor Lý Huệ Tông to become a Buddhist monk and Lý Chiêu Hoàng, Huệ Tông's 8-year-old young daughter, to become ruler of the country.^[155] Trần Thủ Độ then arranged the marriage of Chiêu Hoàng to his nephew Trần Cảnh and eventually had the throne transferred to Trần Cảnh, thus begun the Trần dynasty.^[156] The Trần dynasty, officially Great Việt, was a Vietnamese dynasty that ruled from 1225 to 1400. The Trần dynasty defeated three Mongol invasions, most notably during the decisive Battle of Bạch Đằng River in 1288. The final emperor of the dynasty was Thiếu Đế, who was forced to abdicate the throne in 1400, at the age of five years old in favor of his maternal grandfather, Hồ Quý Ly.

The Trần improved Chinese gunpowder,^[157] enabling them to expand southward to defeat and vassalize the Champa.^[158] They also started using paper money for the first time in Vietnam.^[159] The period was considered a golden age in Vietnamese language, arts, and culture.^[160] The first pieces of Chữ Nôm literature were written during this period,^[161] while the introduction of vernacular Vietnamese into the court was established, alongside Chinese.^[162] This laid the foundation for the further development and solidifying of the Vietnamese language and identity.