70 years ago, the Dalai Lama was 14 years old. It's unlikely he ruled much. The Panchen Lama was 11. Unfortunately, he had reincarnated as two different people supported by different factions in Tibet. One of them allied themselves first with the Kuomintang and then with the Communist Party, which eventually helped them have their candidate be recognized officially by the Dalai Lama. When the Dalai Lama (now 23) fled to India in 1959, the Panchen Lama sided with the Chinese government instead and was made chairman of the Preparatory Committee for the Tibet Autonomous Region.

So on the one hand there was a lot of realpolitik in Tibetan theocracy; on the other hand the Chinese government had no qualms about continuing the system so long as it served their own purposes.