Given a passage and a question, find the answer to the question based on the passage. The answer should consist of only one word that lies in the span of only one of the sentences in the passage.

Paragraph: The Tuotuo River ( , p Tuotuo He , lit . '' Tearful River '' is the official headstream of the Yangtze , and flows 358 km ( 222 mi ) from the glaciers of the Gelaindong Massif in the Tanggula Mountains of southwestern Qinghai to the confluence with the Dangqu River to form the Tongtian River . ) In Mongolian , this section of the river known as the Ulaan Moron or the '' Red River '' .
Question: what is the source of the yangtze river
Qinghai