Qinghai (Chinese: 青海; pinyin: Qīnghǎi; Wade–Giles: Ch'ing-Hai), is a province of the People's Republic of China, located in the west of the country. It is named after Qinghai Lake, and was formerly known as Kokonur in English, from the Oirat language. It borders Gansu on the northeast, the Xinjiang on the northwest, Sichuan on the southeast, and the Tibet Autonomous Region on the southwest.

During China's Bronze Age, Qinghai was home to the Kayue culture. The eastern part of the area of Qinghai was under the control of the Han Dynasty about 2000 years ago. It was a battleground during the Tang and subsequent Chinese dynasties when they fought against successive Tibetan tribes.

In the middle of 3rd century CE, nomadic people related to Xianbei migrated to pasture lands around Koko Nur (Qinghai Lake) and established Tuyuhun Kingdom. Since the 7th century, Tuyuhun Kingdom was attacked by both the Tibetan Empire and Tang Dynasty as both of them sought control over trade routes. Military conflicts severely weakened the kingdom and it was incorporated into the Tibetan Empire. After the disintegration of the Tibetan Empire, small local factions emerged. They were under titular authority of China and Tibet but maintained their autonomy. During the period of Mongol Yuan Dynasty's administrative rule of Tibet, majority of Qinghai belonged to one of the three commandaries of the Tibetan region divided at that time, namely Amdo (Tibetan: ཨ༌མདོ; Chinese: 安多; pinyin: Ānduō).

Most of Qinghai was once also under the control of early Ming Dynasty, but later gradually lost to the Khoshut Mongols.

The Xunhua Salar Autonomous County is where the Salar people live in Qinghai. The Salars voluntarily joined the Ming Dynasty. The Salar clan leaders each capitulated to the Ming Dynasty around 1370. The chief of the four upper clans around this time was Han Pao-yuan and Ming granted him office of centurion, it was at this time the people of his four clans took Han as their surname. The other chief Han Shan-pa of the four lower Salar clans got the same office from Ming, and his clans were the ones who took Ma as their surname.

From the late Ming to 1724, a big part of the area that is now Qinghai was under Khoshut Mongol control, but in that year it was conquered by the armies of the Qing Dynasty. It was during 1720s when Xining Prefecture was established and its borders were roughly those of modern Qinghai province. Xining, the capital of modern Qinghai province was built in this period as the administrative center. During the rule of Qing Dynasty, the governor was a viceroy of the Qing Emperor, but the local ethnic groups enjoyed much autonomy. Many chiefs retained their traditional authority, participating in local administrations. The Dungan revolt (1895–1896) broke out in Qinghai in 1895. The Dungan Revolt (1895) was a rebellion of various Muslim ethnic groups in Qinghai and Gansu against the Qing Dynasty. Following the overthrow of the Qing Dynasty, the region came under Chinese Muslim warlord Ma Qi control until the Northern Expedition by the Republic of China consolidated central control in 1928.

In July-August 1912, General Ma Fuxiang was "Acting Chief Executive Officer of Kokonur" (de facto Governor of the region that later became Qinghai).

In 1928, Qinghai province was created. Previoiusly, it was part of Gansu province, as the "Tibetan frontier district".

The Muslim warlord and General Ma Qi became military governor of Qinghai, followed by his brother Ma Lin (warlord) and then Ma Qi's son Ma Bufang.

In 1932 Tibet invaded Qinghai, attempting to capture southern parts of Qinghai province, following contention in Yushu, Qinghai over a monastery in 1932. The army of Ma Bufang's defeated the Tibetan armies.

Governor of Qinghai, Ma Bufang was described as a socialist by American journalist John Roderick and friendly compared to the other Ma Clique warlords. Ma Bufang was reported to be good humoured and jovial in contrast to the brutal reign of Ma Hongkui.

Most of eastern China was ravaged by the Second Sino-Japanese War the Chinese Civil War, by contrast, Qinghai was relatively untouched.

Ma Bufang increased the prominence of the Hui and Salar people in Qinghai's politics by heavily recruiting to his army from the counties in which those ethnic groups predominated. General Ma started a state run and controlled industralization project, directly creating educational, medical, agricultural, and sanitation projects, run or assisted by the state. The state provided money for food and uniforms in all schools, state run or private. Roads and a theater were constructed. The state controlled all the press, no freedom was allowed for independent journalists. His regime was dictatoral in its political system. Barnett admitted that the regime had "sterm authoritarianism" and "little room for personal freedom".

After the 1949 Chinese revolution, control over Qinghai acceded from the Republic of China to the People's Republic of China. Kuomintang resistance in Qinghai by Ma Bufang and Ma Jiyuan was defeated in the Lanzhou Campaign. Aside from some minor adjustments to suit the geography, the PRC maintained the province's territorial integrity.

Qinghai has been influenced by the interactions "between Mongol and Tibetan culture, north to south, and Han Chinese and Inner Asia Muslim culture, east to west". The languages of Qinghai have for centuries formed a Sprachbund, with Zhongyuan Mandarin, Amdo Tibetan, Salar, Yugur, and Monguor borrowing from and influencing one another. The main religions in Qinghai are Tibetan Buddhism and Islam. Measures of education in Qinghai are low, particularly among the Muslim ethnic groups such as the Hui and Salar, who sometimes prefer to send their children to madrasahs rather than secular schools. The yak, which is native to Qinghai, is widely used in the province for transportation and its meat.

Qinghai is located on the northeastern part of the Qinghai-Tibet Plateau. The Yellow River originates in southern part of the province, while the Yangtze and Mekong have their sources in the southwestern part. Qinghai is separated by the Riyue Mountain (Chinese: 日月山; pinyin: Rìyuè Shān; literally "Sun and moon mountain") into pastoral and agricultural zones in the west and east.

The average elevation of Qinghai is over 3,000 metres (9,800 ft) above sea level. Mountain ranges include the Tanggula Mountains and Kunlun Mountains. Due to the high altitude, Qinghai has quite cold winters (harsh in the highest elevations), mild summers, and a large diurnal temperature variation. Its mean annual temperature is approximately −5 to 8 °C (23 to 46 °F), with January temperatures ranging from −18 to −7 °C (-0 to 19 °F) and July temperatures ranging from 15 to 21 °C (59 to 70 °F). It is also prone to heavy winds as well as sandstorms from February to April. Significant rainfall occurs mainly in summer, while precipitation is very low in winter and spring, and is generally low enough to keep much of the province semi-arid or arid.

By area, Qinghai is the largest province in China - excluding the autonomous regions, which are technically not provinces; but if they were, Xinjiang would be the largest.

Qinghai Lake (Koko Nor) is the largest salt water lake in China, and the second largest in the world.

Qaidam basin lies in northwestern Qinghai. About a third of this resource rich basin is desert. The basin has an altitude between 3000 to 3500 meters.

The Sanjiangyuan National Nature Reserve (SNNR), also referred to as the Sanjiangyuan Nature Reserve, or the Three Rivers Nature Reserve, is the area of Qinghai province, PRC which contains the headwaters of the Yellow River (Huang He), the Yangtze River (Chang Jiang), and the Mekong River (Lancang Jiang). The SNNR was established to protect the headwaters of these three rivers. The reserve consists of 18 subareas, each containing three zones which are managed with differing degrees of strictness.

Bordering Provinces

Northeast-Gansu

Southeast-Sichuan

Southwest-Tibet

Northwest-Xinjiang