Borders of China in the context of "China–Vietnam border"

China, officially the People's Republic of China (PRC), is a country in East Asia. With a population exceeding 1.4 billion, it is the second-most populous country after India, representing 17% of the world population. China borders fourteen countries by land across an area of 9.6 million square kilometers (3,700,000 sq mi), making it the third-largest country by area. The country is divided into 33 province-level divisions: 22 provinces, 5 autonomous regions, 4 municipalities, and 2 semi-autonomous special administrative regions. Beijing is the capital, while Shanghai is the most populous city by urban area and largest financial center.

China saw the first humans in the region arriving during the Paleolithic era. By the 2nd millennium BCE dynastic states had emerged in the Yellow River basin. The 8th–3rd centuries BCE saw a breakdown in the authority of the Zhou dynasty, accompanied by the emergence of administrative and military techniques, literature and philosophy. In 221 BCE, China was unified under an emperor, ushering in two millennia of imperial dynasties. With the invention of gunpowder and paper, the establishment of the Silk Road, and the Great Wall, Chinese culture flourished and has heavily influenced its neighbors and lands further afield. China began to cede parts of the country in the 19th century, to European powers by a series of unequal treaties. The 1911 Revolution overthrew the Qing dynasty and the Republic of China was established the following year. The country was unstable and fragmented during the Warlord Era, which ended upon the Northern Expedition conducted by the Kuomintang to reunify the country.

Russia, the largest country in the world by area, has international land borders with fourteen sovereign states as well as two narrow maritime boundaries with the United States and Japan. There are also two breakaway states bordering Russia, namely Abkhazia and South Ossetia. The country has an internationally recognized land border running 22,407 kilometres (13,923 mi) in total, and has the second-longest land border of any country in the world, after China (22,457 kilometres (13,954 mi)).

The borders of the Russian Federation (formerly the Russian SFSR) were mostly drawn since 1956 (save for minor border changes, e.g., with China), and have remained the same after the dissolution of the Soviet Union. In 2014, Russia annexed Ukraine's Crimean peninsula and parts of Donetsk and Luhansk oblasts in a move that remains internationally unrecognized, but which altered de facto borders with Ukraine. In 2022, Russia further annexed Donetsk, Kherson, Luhansk and Zaporizhzhia oblasts further changing de facto borders with Ukraine.

Xinjiang, officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), in the northwest of the country at the crossroads of Central Asia and East Asia. The largest province-level division of China by area and the 8th-largest country subdivision in the world, Xinjiang spans over 1.6 million square kilometres (620,000 sq mi) and has about 25 million inhabitants. Xinjiang borders the countries of Afghanistan, India, Kazakhstan, Kyrgyzstan, Mongolia, Pakistan, Russia, and Tajikistan. The rugged Karakoram, Kunlun, and Tian Shan mountain ranges occupy much of Xinjiang's borders, as well as its western and southern regions. The Aksai Chin and Trans-Karakoram Tract regions are claimed by India but administered by China. Xinjiang also borders the Tibet Autonomous Region and the provinces of Gansu and Qinghai. The best-known route of the historic Silk Road ran through the territory from the east to its northwestern border.

High mountain ranges divide Xinjiang into the Dzungarian Basin (Dzungaria) in the north and the Tarim Basin in the south. Only about 9.7% of Xinjiang's land area is fit for human habitation. It is home to a number of ethnic groups, including the Han Chinese, Hui, Kazakhs, Kyrgyz, Mongols, Russians, Sibe, Tajiks (Pamiris), Tibetans, and Uyghurs. There are more than a dozen autonomous prefectures and counties for minorities in Xinjiang. Many older English-language reference works call the area Chinese Turkestan, Chinese Turkistan, East Turkestan or East Turkistan.

The borders of Brazil are the international borders that Brazil shares with neighbouring countries. Brazil has terrestrial boundaries with nine countries of South America, and with the French Department of Guiana. Brazil has borders with every country in South America with the exception of Chile and Ecuador, totalling 16,885 kilometres (10,492 mi). Brazil has the world's third longest land border, behind China and Russia.