Read this: In 1904, a British expedition to Tibet, spurred in part by a fear that Russia was extending its power into Tibet as part of The Great Game, invaded the country, hoping that negotiations with the 13th Dalai Lama would be more effective than with Chinese representatives. When the British-led invasion reached Tibet on December 12, 1903, an armed confrontation with the ethnic Tibetans resulted in the Massacre of Chumik Shenko, which resulted in 600 fatalities amongst the Tibetan forces, compared to only 12 on the British side. Afterwards, in 1904 Francis Younghusband imposed a treaty known as the Treaty of Lhasa, which was subsequently repudiated and was succeeded by a 1906 treaty signed between Britain and China.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Who invaded Tibet in 1940?
unanswerable