From almost 100 years ago, the 1911 edition of the Encyclopedia Britannica mentions under the article on China. The Encylopedia Britannica is considered one of the best encylopedias in existence. This article was written long before any modern politics got in the way.
http://www.1911encyclopedia.org/China%2C_Asia
CHINA, a country of eastern Asia, the principal division of the Chinese empire. In addition to China proper the Chinese Empire includes Manchuria, Mongolia, Tibet and Sin-kiang (East Turkestan, Kulja, Dzungaria, &c., i.e. all the Chinese dependencies lying between. Mongolia on the north and Tibet on the south).