Humans inhabited the Tibetan Plateau at least 21,000 years ago. This population was largely replaced around 3,000 BCE by Neolithic immigrants from northern China. However there is a "partial genetic continuity between the Paleolithic inhabitants and the contemporary Tibetan populations". Some archaeological data suggests humans may have passed through Tibet at the time India was first inhabited, half a million years ago. The earliest Tibetan historical texts identify the Zhang Zhung culture as a people who migrated from the Amdo region into what is now the region of Guge in western Tibet, wich is considered to be the original home of the Bön religion. By the 1st century BCE, a neighboring kingdom arose in the Yarlung valley, and the Yarlung king, Drigum Tsenpo, attempted to remove the influence of the Zhang Zhung by expelling the Zhang's Bön priests from Yarlung. He was assassinated and Zhang Zhung continued its dominance of the region until it was annexed by Songtsen Gampo in the 7th century. Prior to Songtsän Gampo, the kings of Tibet were more mythological than factual, and there is insufficient evidence of their existence.
The history of a unified Tibet begins with the rule of Songtsän Gampo (604–650 AD) who united parts of the Yarlung River Valley and founded the Tibetan Empire. He also brought in many reforms and Tibetan power spread rapidly creating a large and powerful empire. In 640 he married Princess Wencheng, the niece of the powerful Chinese emperor Taizong of Tang China.
Under the next few Tibetan kings, Buddhism became established as the state religion and Tibetan power increased even further over large areas of Central Asia, while major inroads were made into Chinese territory, even reaching the Tang's capital Chang'an (modern Xi'an) in late 763. However, the Tibetan occupation of Chang'an only lasted for fifteen days, after which they were defeated by Tang and its ally, the Turkic Uyghur Khaganate.
The Kingdom of Nanzhao (in Yunnan and neighbouring regions) remained under Tibetan control from 750 to 794, when they turned on their Tibetan overlords and helped the Chinese inflict a serious defeat on the Tibetans.
In 747, the hold of Tibet was loosened by the campaign of general Gao Xianzhi, who tried to re-open the direct communications between Central Asia and Kashmir. By 750 the Tibetans had lost almost all of their central Asian possessions to the Chinese. However, after Gao Xianzhi's defeat by the Arabs and Qarluqs at the Battle of Talas (751), Chinese influence decreased rapidly and Tibetan influence resumed. In 821/822 AD Tibet and China signed a peace treaty. A bilingual account of this treaty, including details of the borders between the two countries, is inscribed on a stone pillar which stands outside the Jokhang temple in Lhasa. Tibet continued as a Central Asian empire until the mid-9th century.
MONGOL YUAN DYNASTY
Under the Yuan Dynasty, the ministry of Tibetan governance, or Xuanzheng Yuan, ruled Tibet as a top-level administrative department, in a manner similar to the British Empire and the Raj in India. One of the department's purposes was to select a Dpon-Chen, usually appointed by the lama and confirmed by the Mongol emperor in Beijing. The Sakya lama retained a degree of autonomy, acting as the political authority of the region, while the dpon-chen held administrative and military power. Mongol rule of Tibet remained separate from the main provinces of China, but the region existed under Yuan administration until Ming overthrow of the Yuan. If the Sakya lama ever came into conflict with the dpon-chen, the dpon-chen had the authority to send Chinese troops into the region.
In cultural and spiritual affairs, this rule is characterized as a priest-patron relationship. Mongolian prince Khuden gained temporal power in Tibet in the 1240s and sponsored Sakya Pandita, whose seat became the capital of Tibet.
PHAGMODRUPA DYNASTY AND THE DALAI LAMAS
Between 1346 and 1354, Tai Situ Changchub Gyaltsen toppled the Sakya and founded the Phagmodrupa dynasty. The following 80 years saw the founding of the Gelug school (also known as Yellow Hats) by the disciples of Je Tsongkhapa, and the founding of the important Ganden, Drepung, and Sera monasteries near Lhasa.
In 1578, Altan Khan of the Tümed Mongols gave Sonam Gyatso, a high lama of the Gelugpa school, the name Dalai Lama; Dalai being the Mongolian translation of the Tibetan name Gyatso, or "Ocean".
The first Europeans to arrive in Tibet were the Portuguese missionaries António de Andrade and Manuel Marques in 1624. They were welcomed by the King and Queen of Guge, and were allowed to build a church and to introduce Christian belief. The king of Guge eagerly accepted Christianity as an offsetting religious influence to dilute the thriving Gelugpa and to counterbalance his potential rivals and consolidate his position. All missionaries were expelled in 1745
MANCHU QING DYNASTY
In the 1630s, Tibet became entangled in power struggles between the rising Manchu and various Mongol and Oirat factions. Güshi Khan of the Khoshud became the overlord over Tibet, and acted as a "Protector of the Yellow Church". Güshi helped the fifth Dalai Lama establish himself as the highest spiritual and political authority in Tibet and destroyed any potential rivals.
The Qing Dynasty put Amdo under their control in 1724, and incorporated eastern Kham into neighbouring Chinese provinces in 1728. The Qing government sent a resident commissioner, called an Amban, to Lhasa. In 1750 the Ambans and majority of Chinese and Manchu lived in Lhasa were killed. In 1751, Qing troops arrived quickly and suppressed the rebels. Like the preceding Yuan dynasty, the Manchus of the Qing dynasty exerted military and administrative control of the region, while granting it a degree of political autonomy. The political authority over Tibet was passed to the Dalai Lama leading the government, namely Kashag. The Qing commander publicly executed a number of supporters of the rebels, and, as in 1723 and 1728, made changes in the political structure and drew up a formal organization plan. The Qing now restored the Dalai Lama as ruler but elevated the role of Amban to include more direct involvement in Tibetan internal affairs. At the same time the Qing took steps to counterbalance the power of the aristocracy by adding officials recruited from the clergy to key posts.
For several decades, peace reigned in Tibet, but in 1792 the Qing emperor sent a large Chinese army into Tibet to push the invading Nepalese out. This prompted yet another Qing reorganization of the Tibetan government, this time through a written plan called the "Twenty-Nine Regulations for Better Government in Tibet". Qing military garrisons staffed with Qing troops were now also established near the Nepalese border. Tibet was dominated by the Manchus in various stages in the 18th century, and the years immediately following the 1792 regulations were the peak of the Qing imperial commissioners' authority; but there was no attempt to make Tibet a Chinese province. Nevertheless, as the Qing Dynasty weakened, its authority over Tibet also gradually weakened; by the mid 19th century, its influence was minuscule, and by the late 19th century, Qing authority over Tibet had become more symbolic than real.
The 18th century saw some contact with Jesuits and Capuchins from Europe, and in 1774 a Scottish nobleman, George Bogle, came to Shigatse to investigate trade for the British East India Company.
However, by the 19th century the situation of foreigners in Tibet grew more tenuous. The British Empire was encroaching from northern India into the Himalayas, the Emirate of Afghanistan and the Russian Empire were expanding into Central Asia and each power became suspicious of the others' intentions in Tibet. Sándor Kőrösi Csoma, a Hungarian scientist, spent 20 years in British India (4 years in Ladakh) trying to visit Tibet. He created the first Tibetan-English dictionary.
In 1865, the British began secretly mapping Tibet.
FIRST HALF OF THE 20TH CENTURY
In 1904, a British expedition to Tibet under the command of Colonel Francis Younghusband, accompanied by a large military escort, invaded Tibet and reached Lhasa. The British were spurred in part by a fear that Russia was extending its power into Tibet, and partly by hope that negotiations with the 13th Dalai Lama would be more effective than with Chinese representatives. But on his way to Lhasa, Younghusband slaughtered many Tibetan troops in Gyangzê who tried to stop the British advance. When the mission reached Lhasa, Younghusband imposed a treaty which was subsequently repudiated, and was succeeded by a 1906 treaty signed between Britain and China.
In 1910, the Qing government sent a military expedition of its own under Zhao Erfeng to establish direct Chinese rule and deposed the Dalai Lama in an imperial edict, who fled to British India. Zhao Erfeng defeated the Tibetan military conclusively and expelled the Dalai Lama's forces from the province, he was nicknamed "Zhao the Butcher" for crushing the Tibetan army.
After the Xinhai Revolution (1911-12) toppled the Qing and the last Qing troops were escorted out of Tibet, the new Republic of China apologized for the actions of the Qing and offered to restore the Dalai Lama's title. The Dalai Lama refused any Chinese title, and declared himself ruler of an independent Tibet in collusion with Mongolia. For the next thirty-six years, the 13th Dalai Lama and the regents who succeeded him governed Tibet, while China endured its Warlord era, civil war, and invasion by Japan. During this time, Tibet fought Chinese warlords for control of the ethnically Tibetan areas in Xikang and Qinghai (parts of Kham and Amdo); the resulting boundary was unstable but for the most part was along the upper reaches of the Yangtze River.
When the regents in the 1930s and 40s displayed negligence in affairs, the Kuomintang Government of the Republic of China used this to their advantage to expand their reach into the Lhasa regime of the Dalai Lama. The policy of the 13th Dalai Lama towards the central Chinese government did not command universal approval in Tibet. Tensions and factions within the regime in Lhasa led to an attempted coup in 1947. A faction which backed the former Regent, Reting Rimpoche, sent a bomb to the current Regent, which exploded before it could be delivered. Reting was arrested, imprisoned in the Potala, and died in mysterious circumstances. Troops were sent to the monastery of Sera, from which Reting came, and which surrendered when a bombardment began. Many of its monks fled the region.
SECOND HALF OF THE 20TH CENTURY
Emerging with control over most of mainland China after the Chinese Civil War, the People's Liberation Army confronted the Dalai Lama's army at Qamdo in 1950 and negotiated the Seventeen Point Agreement with the newly crowned 14th Dalai Lama's government, affirming the People's Republic of China's sovereignty but granting the area autonomy. After the Dalai Lama government fled to Dharamsala, India during the 1959 Tibetan Rebellion, he denounced the Seventeen Point Agreement. The Central People's Government also renounced the agreement and began implementation of the halted social and political reforms. This progression was interrupted as the Cultural Revolution saw radical changes in governance and the destruction of the Four Olds in nearly all of mainland China, including in Tibet, until the faction that led the Revolution was ousted from power. In 1980, General Secretary and reformist Hu Yaobang visited Tibet, and ushered in a period of social, political, and economic liberalization. Free practice of religion was allowed, monasteries were rebuilt, and the government stopped jamming foreign Tibetan language radio broadcasts. At the end of the decade, however analogously to the Tiananmen Square protests of 1989, monks in the Drepung and Sera monasteries started protesting for independence, and so the government halted reforms and started an anti-separatist campaign. Human rights organisations have sometimes criticised the Beijing and Lhasa governments' approach to human rights in the region when cracking down on separatism.