Answer:
The claim that China used to justify invading Tibet in 1950 is that Tibet was formerly under the rule of China and so it has all the rights to rule over it.
Explanation:
On 7 October 1950, The Communist Party of China, declared that Tibet should again be made an integral part of China. This led to the Chinese invasion in Tibet thus increasing the cross -border tensions and territorial disputes.
Around 1.6 million of Tibetans were estimated to be killed by china so far.