You're conflating two things. I'm talking about the PRC invasion of Tibet in 1950, after which they agreed to join China. The 1959 uprising is indeed a decade afterwards and involves the total dissolution of any Tibetan autonomy, but prior to 1950 Tibet was claiming themselves as an independent sovereign nation. I'm talking about the Battle of Chamdo in 1950, where the PRC "invaded" Tibet, after which Tibet "joined" China. The 1959 rebellion is clearly a case of the PRC putting down an internal rebellion. The 1950 invasion is a bit murkier, given the confused semi-autonomous status of Tibet at the time.