Ch'ing-hai

The Yellow River (黃河) rises in small lakes in the southern part of Ch'ing-hai (青海) and flows in a very crooked channel toward the north-east to Lan-chou Fu (蘭州府).

Source: wiktionary

Leaving this town and the Sining River valley the road ascends a grassy valley with some recently started cultivation to a pass, 10,780 feet, over the Jih-yüeh Shan range, 27 miles from Tangar. This is the boundary between the Kansu and Ch'ing-hai Provinces. It is also the real boundary between China and Tibet, though the present frontier is the Tang-la Range, running east and west, the divide between the Salween and Mekong rivers.

Source: wiktionary

In the west, the outer periphery of the Inner Zone is the great divide separating Pacific Ocean and South China Sea drainage on the one hand, from drainage oriented towards Hsin-chiang in the northwest and towards the Indian Ocean in the southwest, on the other. This divide also represents a fairly pronounced stress zone between the tenuous power China has been able to maintain over Tibet to the west and the firmer control she has been able to exercise over Hsi-k'ang and Ch'ing-hai to the east.

Source: wiktionary

For centuries the area of ethnic Tibet was divided into the following: Dbus and Gtsang (comprising central Tibet), Mnga’-ris, Khams, and A-mdo.[…]A-mdo, the northeastern part of ethnic Tibet, passed under Manchu control in 1724 following the suppression of a Mongol revolt against the throne. This area was officially incorporated into the Chinese provincial system as Ch’ing-hai Province in 1928.

Source: wiktionary