Three of Asia’s longest rivers, the Yangtse (6,300 km), Yellow River (5,500 km) and Mekong (4,900 km) all have their source in China’s Qinghai province, at the northern part of the Tibetan plateau.
Seems like a remarkable fact. But rivers that start furthest inland and at this highest plateau don’t have much choice but to become the longest on their way to the sea.
Besides all three come from Yushu prefecture (the administrative unit below provincial level). And two of them, the Yangtse and Mekong, even come from the same county of Zaduo (the administrative unit below prefectural level).
This if you accept the length of a river’s longest tributary as the criterion to determine a river’s source.
Introduction of satellite measurements has made establishment of river lengths more easy and more reliable. It has led to the ‘relocation’ of the source of all three rivers. The Dang Qu turns out to be a longer tributary of the Yangtse than the Tuotuo He so that its source, traditionally at Geladandong west of Yushu, moves to Zaduo county. The Kari Qu turns out to be longer than the Yueguzong Qu, shifting the Yellow River’s source to the territory of Yushu. The disagreement about the Mekong’s source doesn’t matter in this respect: it will remain in Zaduo county, whatever the outcome.