When the Chinese were expelled from Tibet

Chinese soldiers leaving Tibet in 1912

One is often asked, do you have any proof that Tibet was an Independent nation during the 20th century.
There are of course, many signs that Tibet was a de facto independent country when the Chinese troops entered Chamdo in October 1950. 
One of them is the expulsion of the Chinese from Lhasa, a first time in 1912 and a second time in 1949.
I quote here from my book, Tibet, the Lost Frontier.

On July 8, 1949, Chen, the acting head of the Chinese mission in Lhasa, was called by the Kashag and informed that he and his staff as well as all Chinese working in schools and hospitals had to leave Tibet. The pretext was that the Chinese Mission no longer had any relations with the Nationalist Government and was not accredited with the new government.
In fact, the Tibetan Government was afraid that some (if not all) members of the Chinese mission in Lhasa would switch over to the new Communist regime in Beijing ‘for bread and butter’, as Richardson put it. The Chinese were swiftly expelled by the Tibetan Government and their bank accounts frozen in India on the request of the Tibetan Government.
The move had been prepared for more than a year by Tsipon Namseling who had made a detailed list of Chinese agents in Lhasa. The remarkable feature was that secret had not leaked out of the Kashag Office during all that time. It was a record of sorts for a small village like Lhasa.
The Indian Mission was later informed about the fait accompli. “It was a complete surprise for the Indian Mission”, [Hugh] Richardson [the Head of the Indian Mission in Tibet] commented later.
However the Chinese were expelled with courtesy and a band accompanied them until they were outside of Lhasa.
The cable that Nehru sent to the Political Officer in Sikkim demonstrates the position of the Government of India vis-à-vis Tibet in 1949 and makes interesting reading:

2. We are concerned over the Tibetan Government's decision to turn out all Chinese officials in Lhasa.[It was reported that the Head of Tibetan State Department at Lhasa had shut off the Nationalist Radio Station in Lhasa on 8 July 1949, asked the Nationalist Government's branch office to close down and ordered all officers to leave.] These officials were appointed by the National Government of China. Their wholesale expulsion will naturally be regarded as an anti-Chinese rather than anti-Communist move. And the Government of India, by letting them into India without any travel papers in contravention of all passport regulations, will be regarded as privy to this move.
3. We can however understand the desire of the Tibetan Government to get rid of persons suspected of subversive tendencies and officials sympathizing with them. From the Tibetan Government's own point of view it would seem better for Tibetans to expel these suspects rather than all Chinese officials in Lhasa.

Nehru was ready to help to a certain extent; he informed the Political Officer in Sikkim that “there are many difficulties in the way of the Government of India receiving and looking after these suspects. Nevertheless, in view of our friendly relations with the Tibetan Government, we are considering the possibility of giving them passage. We would be gravely embarrassed if they stayed in India. We shall require advance information of the names and particulars of the persons concerned, some indication of the charges against them, and the place or places to which they will proceed.”
He concluded by suggesting:

… that unless you or Richardson have any further comments the position of the Government of India should be tactfully explained to the Tibetan Government. The Tibetan Government are the best judges of their own interests but to us it would seem unwise on their part to take any steps which in effect mean the forced discontinuance of the Chinese Mission in Lhasa. The objects of the Tibetan Government will be served by expelling the suspects and officials associated with them. If any of the Chinese, left behind, indulge in objectionable activities they can also be similarly dealt with. Such gradual and considered action will appear justified in the eyes of the world, but not the precipitate action now contemplated.

It is clear that a few months before the Fateful Year of 1950, the Government of India, “in view of [its] friendly relations with the Tibetan Government”, was ready to help Lhasa with its security concerns. Not only Delhi treated Tibet as an independent entity, but the Government of India accepted that they were the best judge of their problems.