China claims Tibet's territory, not as a result of the invasion of 1949 - 1951, but by 'historical right.' This 'right' ignores all the treaties signed between the two countries, and the fact of Tibet's conquest of China in the Tang dynasty. The China-Tibet Peace Treaty of 821 AD established border markers (which still exist) bearing the text of the treaty which stated, 'Tibetans shall be happy in Tibet and Chinese shall be happy in China.' The reasons why the Chinese want to hold on to Tibet so desperately might seem puzzling.
The usual events cited by the Chinese are:
The marriage of King Songtsen Gampo to Princess Wengchen in 641 AD. In fact, she was only the second of his many wives, and was taken as part of the peace treaty he imposed on the Chinese after his victory over the Tang armies.
The fact that Tibet submitted to Mongol leader Godan Khan after the Mongols conquered North China in 1240. The Mongols finalised their conquest of China in 1270, and ruled China directly, while leaving Tibet to govern itself under the Sakya Lama-kings. China's claim to Tibet because both countries were invaded by the Mongols is as logical as saying that Ireland should rule India because both were invaded and colonised by Britain.
The fact that the Mongol Emperor Altan Khan bestowed the title of Dalai Lama on Gelugpa leader Sonam Gyatso in 1578. Recent Chinese interpretations of period pictures of this event state that the Dalai Lama was 'submitting' to Altan Khan. In fact, the relationship was termed that of 'Priest' and 'Patron,' with the understanding that the priest took primacy in spiritual matters, where the patron took primacy in temporal matters.
As regards 'submitting' to the Chinese Emperors, it is worth noting that in 1793 Lord Macartney visited the court of Qing Emperor Qian Long to try to establish trade links with Britain. Rejecting the need for trade with Britain, the Emperor considered Macartney's visit an act of 'submission,' and wrote to King George III, 'By perpetual submission to our Throne, you may secure peace and prosperity for your country thereafter.'
This same Emperor Qian Long was a very devout Buddhist and considered the Dalai Lama to be his priest, and himself the Dalai Lama's patron-protector.
The new republic of China 'claimed' Tibet and Mongolia as the last Qing Emperor, Pu Yi, abdicated in 1912. However, Tibet and Mongolia both proclaimed their independence and recognised each other in the Treaty of Urga signed in 1913. Chinese Republic President Sun Yat-sen declared that all 'national minorities' should have full autonomy.
In 1914, Britain recognised Tibet as an independent nation at the signing of the Simla agreement, which established the McMahon Line as the border between Tibet and India.
At this time, of the three Tibetan provinces (U-Tsang, Amdo and Kham) Kham fell under the influence of Chinese warlords, who were defeated and expelled by the Tibetans in 1918. Chiang Kai-shek signed a truce with Tibet in 1933, and in 1934 China was allowed to open a diplomatic mission in Lhasa, the first since the expulsion of the ambans in 1912.
All of which shows that China did not treat Tibet as an integral part of its own territory before the invasion of 1949 - 1951. As Irish Foreign Minister, Frank Aiken said at the UN General Assembly in 1959: 'Looking around this assembly, and looking at my own delegations, I think how many benches would be empty in this hall if it had always been agreed that when a small nation or a small people feel in the grip of a major power no one could ever raise their voice here; that once there was a subject nation, they must always remain a subject nation. Tibet has fallen into the hands of the Chinese People's Republic for the last few years. For thousands of years, or for a couple of thousand of years at any rate, it was as free and as fully in control of its own affairs as any nation in this Assembly, and a thousand times more free to look after its own affairs than many of the nations here.'
The fact of the matter is that Tibet, historically, is a distinct nation, racially, linguistically, and culturally, separated from China not just by these factors, but also by virtue of its geographical location, the vast high plateau surrounded by the Himalayas, the Karakorams, the Kunlun, and Tanggla mountain ranges. Its political identity was also distinct, and independent, (Tibet had its own currency, postal system, and passports) before the PRC invasion and occupation of 1949, which reduced Tibet to the status of a Chinese colony.