Qing is Manchu empire, not chinese. Manchu(Qing) just conqured China(Ming) like Mongols did. Manchu are not chinese. Manchu language is radically different from Chinese, and they used Manchu letters. Yuan is a Mongolian country, likewise, Qing is a Manchu country. China was just governed by Mongol and Manchu empires. So, Tibet had never been part of China until China invaded Tibet in 1950s.