Champa in the context of Văn Lang

Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of Mainland Southeast Asia. With an area of about 331,000 square kilometres (128,000 sq mi) and a population of over 100 million, it is the world's 15th-most populous country. One of two communist states in Southeast Asia, Vietnam is bordered by China to the north, Laos and Cambodia to the west, the Gulf of Thailand to the southwest, and the South China Sea to the east; it also shares maritime borders with Thailand, Malaysia, and Indonesia to the south and southwest, the Philippines to the east, and China to the northeast. Its capital is Hanoi, while its largest city is Ho Chi Minh City.

Vietnam was inhabited by the Paleolithic age, with states established in the first millennium BC on the Red River Delta in modern-day northern Vietnam. The Han dynasty annexed northern and central Vietnam, which were subsequently under Chinese rule from 111 BC until the first dynasty emerged in 939. Successive monarchical dynasties absorbed Chinese influences through Confucianism and Buddhism, and expanded southward to the Mekong Delta, conquering Champa. During most of the 17th and 18th centuries, Vietnam was effectively divided into two domains of Đàng Trong and Đàng Ngoài. The Nguyễn—the last imperial dynasty—surrendered to France in 1883. In 1887, its territory was integrated into French Indochina as three separate regions. In the immediate aftermath of World War II, the Viet Minh, a coalition front led by the communist revolutionary Ho Chi Minh, launched the August Revolution and declared Vietnam's independence from the Empire of Japan in 1945.

Srivijaya (Indonesian: Sriwijaya), also spelled Sri Vijaya or Sriwijaya, was a Malay thalassocratic empire based on the island of Sumatra (in modern-day Indonesia) that influenced much of Southeast Asia. Srivijaya was an important centre for the expansion of Buddhism from the 7th to 11th century AD. Srivijaya was the first polity to dominate much of western Maritime Southeast Asia. Due to its location, Srivijaya developed complex technology using maritime resources. In addition, its economy became progressively reliant on the booming trade in the region, thus transforming it into a prestige goods-based economy.

The earliest reference to it dates from the 7th century. A Tang dynasty Chinese monk, Yijing, wrote that he visited Srivijaya in 671 for six months. The earliest known inscription in which the name Srivijaya appears also dates from the 7th century in the Kedukan Bukit inscription found near Palembang, Sumatra, dated 16 June 682. Between the late 7th and early 11th century, Srivijaya rose to become a hegemon in Southeast Asia. It was involved in close interactions, often rivalries, with the neighbouring Mataram Kingdom, Khmer Empire and Champa. Srivijaya's main foreign interest was nurturing lucrative trade agreements with China which lasted from the Tang to the Song dynasty. Srivijaya had religious, cultural and trade links with the Buddhist Pala of Bengal, as well as with the Islamic Caliphate in the Middle East.

Cham (Cham: ꨌꩌ, Jawi: چم, Latin script: Cam) is a Malayo-Polynesian language of the Austronesian family, spoken by the Chams of Southeast Asia. It is spoken primarily in the territory of the former Kingdom of Champa, which spanned modern Southern Vietnam, as well as in Cambodia by a significant population which descends from refugees that fled during the decline and fall of Champa. The Western variety is spoken by 220,000 people in Cambodia and 25,000 people in Vietnam. As for the Eastern variety, there are about 73,000 speakers in Vietnam, for a total of approximately 491,448 speakers.

Cham belongs to the Chamic languages, which are spoken in parts of mainland Southeast Asia, Indonesia's Aceh Province, and on the island of Hainan. Cham is the oldest-attested Austronesian language, with the Đông Yên Châu inscription being verifiably dated to the late 4th century AD. It has several dialects, with Eastern Cham (Phan Rang Cham; ꨌꩌ ꨚꨰ, Cam pai) and Western Cham (ꨌꩌ ꨚꨭꩉ, Cam pur) being the main ones. The Cham script, derived from the ancient Indic script, is still used for ceremonial and religious purposes.

The term mandala (Sanskrit: मंडल, romanized: maṇḍala, lit. 'circle') is used to describe a model of decentralized political systems in the early historical era of medieval Southeast Asia. At that time, authority radiated from a core centre rather than being defined by fixed territorial boundaries. This model emphasizes the fluid distribution of power among the networks of Mueang and Kedatuan city-states or principalities, in contrast to modern concepts of centralized nation-states.

The mandala model was adopted by 20th-century historians as a way to analyse traditional structures (such as federations of kingdoms or tributary states) without imposing preconceived notions of statehood. Unlike Chinese and European models of a state, with fixed borders and centralized bureaucracies, most Southeast Asian polities operated by means of overlapping spheres of influence. Their sovereignty was derived from an ability to attract allegiance using cultural, economic, or military prestige, rather than by means of land control. These dynamic systems could incorporate multiple subordinate centres, while maintaining a symbolic "centre of domination". The centre was often embodied by a ruler's court or sacred site.

The Nguyễn lords (Vietnamese: Chúa Nguyễn, 主阮; 1558–1777, 1780–1802), also known as the Nguyễn clan (Vietnamese: Nguyễn thị; chữ Hán: 阮氏), were Nguyễn dynasty's forerunner and a feudal noble clan ruling southern Đại Việt in the Revival Lê dynasty. The Nguyễn lords were members of the House of Nguyễn Phúc. The territory they ruled was known contemporarily as Đàng Trong (Inner Realm) and known by Europeans as the Kingdom of Cochinchina and as Kingdom of Quảng Nam (Vietnamese: Quảng Nam Quốc; chữ Hán: 廣南國) by Imperial China, in opposition to the Trịnh lords ruling northern Đại Việt as Đàng Ngoài (Outer Realm), known as the "Kingdom of Tonkin" by Europeans and "Kingdom of Annam" (Vietnamese: An Nam Quốc; chữ Hán: 安南國) by Imperial China in bilateral diplomacy. They were officially entitled, in Sino-Vietnamese, the Nguyễn Vương (chữ Hán: 阮王) in 1744 when lord Nguyễn Phúc Khoát self-proclaimed himself to elevate his status equally to Trịnh lords's title known as the Trịnh Vương (Vietnamese: Trịnh Vương; chữ Hán: 鄭王). Both Nguyễn and Trịnh clans were de jure subordinates and fief of the Lê dynasty. However, the de jure submission of the Nguyễn lords to the Trịnh lords ended in 1627 sparked the war between them.

While they recognized the authority of and claimed to be loyal subjects of the revival Lê dynasty, they were de facto rulers of southern Đại Việt. Meanwhile, the Trịnh lords ruled northern Đại Việt in the name of the Lê emperor, who was in reality a puppet ruler. They fought a series of long and bitter wars that pitted the two halves of Vietnam against each other. The Nguyễn were finally overthrown in the Tây Sơn wars, but one of their descendants would eventually come to unite all of Vietnam. Their rule consolidated earlier southward expansion into Champa and pushed southwest into Cambodia.

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. 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".

The first Mongol invasions of Burma (Burmese: မွန်ဂို–မြန်မာ စစ် (၁၂၇၇–၁၂၈၇); Chinese: 元緬戰爭) were a series of military conflicts between Kublai Khan's Yuan dynasty, a division of the Mongol Empire, and the Pagan Empire that took place between 1277 and 1287. The invasions toppled the 250-year-old Pagan Empire, and the Mongol army seized Pagan territories in present-day Dehong, Yunnan and northern Burma to Tagaung. The invasions ushered in 250 years of political fragmentation in Burma and the rise of ethnic Tai-Shan states throughout mainland Southeast Asia.

The Mongols first demanded tribute from Pagan in 1271–1272, as part of their drive to encircle the Song dynasty of China. When King Narathihapate refused, Emperor Kublai Khan himself sent another mission in 1273, again demanding tribute. It too was rejected. In 1275, the emperor ordered the Yunnan government to secure the borderlands in order to block an escape path for the Song, and permitted a limited border war if Pagan contested. Pagan did contest but its army was driven back at the frontier by the Mongol army in 1277–1278. After a brief lull, Kublai Khan in 1281 again turned his attention to Southeast Asia, demanding tribute from Pagan, the Khmer Empire, Đại Việt and Champa. When the Burmese king again refused, the emperor ordered an invasion of northern Burma. Two dry season campaigns (1283–1285) later, the Mongols had occupied down to Tagaung and Hanlin, forcing the Burmese king to flee to Lower Burma. The Mongols organized northern Burma as the province of Zhengmian.

The Cham–Vietnamese Wars were a series of wars and conflicts between various Vietnamese dynasties and of Champa that led to a total annexation of Champa by the Vietnamese, starting with the 10th-century wars between the two states, and ended with recent 20th-century ethnic conflicts. These wars are considered principal parts of the Vietnamese's supposed Nam tiến (March to the South) theory.