Nam tiến (Vietnamese: [nam tǐən]; chữ Hán: 南進; lit. "southward advance" or "march to the south") is a historiographical concept that describes the historic southward expansion of the territory of Vietnamese dynasties' dominions and ethnic Kinh people (Đại Việt) from the 11th to the 19th centuries. The concept of Nam tiến has differing interpretations, with some equating it to Vietnamese colonization of the south and to a series of wars and conflicts between several Vietnamese dynasties and Champa Kingdoms, which resulted in the annexation and Vietnamization of the former Cham states, as well as indigenous territories such as those inhabited by the Khmer Krom. The nam tiến became one of the dominant themes of the narrative that Vietnamese nationalists created in the 20th century, alongside an emphasis on non-Chinese origin and Vietnamese homogeneity. Within Vietnamese nationalism and Greater Vietnam ideology, it served as a romanticized conceptualization of the Vietnamese identity, especially in South Vietnam and modern Vietnam.
The Vietnamese domain gradually expanded from its original heartland in the Red River Delta into southern territories, which were controlled by the Champa kingdoms. In a span of some 700 years, the Vietnamese domain tripled the area of its territory and more or less acquired the elongated shape of modern-day Vietnam. Beginning in the 20th century, modern Vietnamese historiography, under the auspices of nationalism and racialism, coined the term Nam tiến for what they believed to be a gradual, inevitable southern expansion of Vietnamese domains. According to the 20th-century Vietnamese scholars who constructed the Nam tiến as a continuous historical phenomenon, the 11th to the 14th centuries saw battle gains and losses as frontier territory changed hands between the Viet and the Chams during the early Cham–Viet wars. In the 15th, 16th and 17th centuries, following the Fourth Chinese domination of Vietnam (1407–1427), the Vietnamese defeated the less centralized state of Champa and seized its capital in the 1471 Cham–Vietnamese War. From the 17th to the 19th centuries, Vietnamese settlers penetrated the Mekong Delta. The Nguyễn lords of Huế wrested the southernmost territory from Cambodia by diplomacy and by force, which completed the "March to the South".
