魏源
"Zhongguo" appeared in a formal international legal document for the first time during the Qing dynasty in the Treaty of Nerchinsk, 1689. The term was then used in communications with other states and in treaties. The Manchu rulers incorporated Inner Asian polities into their empire, and Wei Yuan, a statecraft scholar, distinguished the new territories from "Zhongguo", which he defined as the 17 provinces of "China proper" plus the Manchu homelands in the Northeast. By the late 19th century the term had emerged as a common name for the whole country. The empire was sometimes referred to as Great Qing but increasingly as "Zhongguo" (see the discussion below).