Red River Delta in the context of "Cát Hải"

The history of China spans several millennia across a wide geographical area. Each region now considered part of the Chinese world has experienced periods of unity, fracture, prosperity, and strife. Chinese civilization first emerged in the Yellow River valley, which along with the Yangtze basin constitutes the geographic core of the Chinese cultural sphere. China maintains a rich diversity of ethnic and linguistic people groups. The traditional lens for viewing Chinese history is the dynastic cycle: imperial dynasties rise and fall, and are ascribed certain achievements. This lens also tends to assume Chinese civilization can be traced as an unbroken thread many thousands of years into the past, making it one of the cradles of civilization. At various times, states representative of a dominant Chinese culture have directly controlled areas stretching as far west as the Tian Shan, the Tarim Basin, and the Himalayas, as far north as the Sayan Mountains, and as far south as the delta of the Red River.

The Neolithic period saw increasingly complex polities begin to emerge along the Yellow and Yangtze rivers. The Erlitou culture in the central plains of China is sometimes identified with the Xia dynasty (3rd millennium BC) of traditional Chinese historiography. The earliest surviving written Chinese dates to roughly 1250 BC, consisting of divinations inscribed on oracle bones. Chinese bronze inscriptions, ritual texts dedicated to ancestors, form another large corpus of early Chinese writing. The earliest strata of received literature in Chinese include poetry, divination, and records of official speeches. China is believed to be one of a very few loci of independent invention of writing, and the earliest surviving records display an already-mature written language. The culture remembered by the earliest extant literature is that of the Zhou dynasty (c. 1046 – 256 BC), China's Axial Age, during which the Mandate of Heaven was introduced, and foundations laid for philosophies such as Confucianism, Taoism, Legalism, and Wuxing.

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.

Chữ Hán (Vietnamese: 𡨸漢 [t͡ɕɯ˦ˀ˥ haːn˧˦] , lit. 'Han characters') are the Chinese characters that were used to write Literary Chinese (Hán văn; 漢文) and Sino-Vietnamese vocabulary in Vietnamese. They were officially used in Vietnam after the Red River Delta region was incorporated into the Han dynasty and continued to be used until the early 20th century.

Thái Bình river (Vietnamese: Sông Thái Bình) is the name of the Thái Bình river system's main river in Northern Vietnam. This river system joins with the Red River system and brings alluvium to create Red River Delta.

Thái Bình river starts in the area of Đồng Phúc commune, Yên Dũng District, Bắc Giang Province – where the Thuong River and Cầu River join with each other. It then flows to Hải Dương Province and becomes the boundary between Bắc Giang and Hải Dương. After flowing through the area of Hải Dương, it enters Thái Bình Province and flows to the South China Sea at Ba Lat river mouth.

Northern Vietnam or Tonkin (Vietnamese: Bắc Bộ) is one of three geographical regions in Vietnam. It consists of three geographic sub-regions: the Northwest (Vùng Tây Bắc), the Northeast (Vùng Đông Bắc), and the Red River Delta (Đồng Bằng Sông Hồng). It is near China. Unlike tropical Central and Southern Vietnam, Northern Vietnam has a subtropical climate.

It has a total area of about 109,942.9 km. The region's largest city, Hanoi, serves as the country's capital. Among the three geographical regions, the oldest is Northern Vietnam. Vietnamese culture originated in the Red River Delta and the Kinh Vietnamese eventually spread south into the Mekong Delta.

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.