Tibet is known to be a part of China. This is one of the autonomous regions that you can find there. There was a time when Tibet and China were two different countries, but this changed back in the 1950s.
China is known to be one of the most powerful countries in the world right now, especially since its economy is getting bigger and better over the past years. The government of China rules over other countries, which include Tibet. There are also other countries that are under the governance of China, such as Hong Kong. There are different motives and reasons why China and Tibet have decided to merge together. It is definitely strategic for China to do this.