In history, Mongolian took over almost the whole Eu-As continent,including China,but finally,the emperor disbanded Europe and middle east,leaving the land of Mongle and China now.Then Chinese defeated them and ruled both of the 2 races.They departed from Chinese just at the beginning of the WWII with the help of Russia.
And tibet is part of China, search on the internet,and see the world map.
my English is bad, but i think what I said is clearly enough