Northern Vietnam in the context of "Trung sisters' rebellion"

The Red River Delta or Hong River Delta (Vietnamese: Đồng bằng sông Hồng) is the flat low-lying plain formed by the Red River and its distributaries merging with the Thái Bình River in Northern Vietnam. Hồng (紅) is a Sino-Vietnamese word for "red" or "crimson". The delta has the smallest area but highest population and population density of all regions in Vietnam. The region, measuring some 15,000 square kilometres (6,000 sq mi) is well protected by a network of dikes. It is an agriculturally rich and densely populated area. Most of the land is devoted to rice cultivation.

Eight provinces, together with two municipalities (the capital Hanoi, and the port of Haiphong) form the delta. It had a population of almost 23 million in 2019.

Emperor Wu of Han (156 – 29 March 87 BC), personal name Liu Che and courtesy name Tong, was the seventh emperor of the Han dynasty from 141 to 87 BC. His reign lasted 54 years – a record not broken until the reign of the Kangxi Emperor more than 1,800 years later – and remains the record for ethnic Han emperors. His reign resulted in a vast expansion of geopolitical influence for the Chinese civilization, and the development of a strong centralized state via governmental policies, economical reorganization and promotion of a hybrid Legalist–Confucian doctrine. In the field of historical social and cultural studies, Emperor Wu is known for his religious innovations and patronage of the poetic and musical arts, including the development of the Imperial Music Bureau into a prestigious entity. It was also during his reign that cultural contact with western Eurasia was greatly increased, directly and indirectly.

During his reign, Emperor Wu led the Han dynasty through its greatest territorial expansion. At its height, the Empire's borders spanned from the Fergana Valley in the west, to northern Korea in the east, and to northern Vietnam in the south. Emperor Wu successfully repelled the nomadic Xiongnu from systematically raiding northern China, and dispatched his envoy Zhang Qian into the Western Regions in 139 BC to seek an alliance with the Greater Yuezhi and Kangju, which resulted in further diplomatic missions to Central Asia. Although historical records do not describe him as being aware of Buddhism, emphasizing rather his interest in shamanism, the cultural exchanges that occurred as a consequence of these embassies suggest that he received Buddhist statues from Central Asia, as depicted in the murals found in the Mogao Caves.

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.

The Vietnamese government often groups the various provinces and municipalities into three regions: Northern Vietnam, Central Vietnam, and Southern Vietnam. These regions can be further subdivided into eight subregions: Northeast Vietnam, Northwest Vietnam, the Red River Delta, the North Central Coast, the South Central Coast, the Central Highlands, Southeast Vietnam, and the Mekong River Delta. These regions are not always used, and alternative classifications are possible. Other classifications used can be: Northern, Central, Southern, and Mekong.

The Vietnamese people (Vietnamese: người Việt, lit. 'Việt people') or the Kinh people (Vietnamese: người Kinh, lit. 'Metropolitan people'), also known as the Viet people or the Viets, are a Southeast Asian ethnic group native to modern-day northern Vietnam and southern China who speak Vietnamese, the most widely spoken Austroasiatic language.

Vietnamese Kinh people account for 85.32% of the population of Vietnam in the 2019 census, and are officially designated and recognized as the Kinh people (người Kinh) to distinguish them from the other minority groups residing in the country such as the Hmong, Cham, or Mường. The Vietnamese are one of the four main groups of Vietic speakers in Vietnam, the others being the Mường, Thổ, and Chứt people. Diasporic descendants of the Vietnamese in China, known as the Gin people, are one of 56 ethnic groups officially recognized by the People's Republic of China, residing in the Guangxi Zhuang Autonomous Region.

The Gulf of Tonkin is a gulf at the northwestern portion of the South China Sea, located off the coasts of Tonkin (northern Vietnam) and South China. It has a total surface area of 126,250 km (48,750 sq mi). It is defined in the west and northwest by the northern coastline of Vietnam down to the Cồn Cỏ island, in the north by China's Guangxi Zhuang Autonomous Region, and to the east by the Leizhou Peninsula and Hainan Island.

English sources from the People's Republic of China refer to the Gulf of Tonkin as Beibu Wan.

The Baiyue, Hundred Yue, or simply Yue, were various ethnic groups who inhabited the regions of southern China and northern Vietnam during the 1st millennium BC and 1st millennium AD. They were known for their short hair, body tattoos, fine swords, and naval prowess.

During the Warring States period, the word "Yue" referred to the state of Yue in Zhejiang. The later kingdoms of Minyue in Fujian and Nanyue in Guangdong were both considered Yue states. During the Zhou and Han dynasties, the Yue lived in a vast territory from Jiangsu to Yunnan, while Barlow (1997:2) indicates that the Luoyue occupied the southwest Guangxi and northern Vietnam. The Book of Han describes the various Yue tribes and peoples can be found from the regions of Kuaiji to Jiaozhi.

Tonkin (chữ Hán: 東京), or Bắc Kỳ (北圻), was a French protectorate encompassing modern Northern Vietnam from 1883 to 1949. Like the French protectorate of Annam, Tonkin was still nominally ruled by the Vietnamese Nguyễn dynasty. In 1886, the French separated Tonkin from the Nguyễn imperial court in Huế by establishing the office of "Viceroy" (經略衙, Kinh lược nha). However, on 26 July 1897, the position of Viceroy was abolished, officially making the French resident-superior of Tonkin both the representative of the French colonial administration and the Nguyễn dynasty court in Huế, giving him the power to appoint local mandarins. In 1887, Tonkin became a part of the Union of Indochina.

In March 1945, the emperor Bảo Đại rescinded the Patenôtre Treaty, ending the French protectorates over Annam and Tonkin, establishing the Empire of Vietnam, a Japanese-backed state. Following the surrender of Japan, ending World War II, the Việt Minh launched the August Revolution which led to the abdication of Bảo Đại and the declaration of independence of the Democratic Republic of Vietnam.