• is at Lasagongma spring, located on Mount Gupzongmucha.
• within the Tibetan Plateau in China’s Qinghai Province.

Mouth of Mekong River;

• is at the South China Sea.
• and the Mekong Delta is in the region in southwestern Vietnam.
  

Mouth of the river is shaded in green

Mekong's Delta

River course of Mekong River;

• Upper Mekong is a long, narrow valley comprising one-fourth of the total area.
• It cuts through the mountains and plateaus of China.
• Lower Mekong, below the point forming the border between Myanmar and Laos, is a stream 1,485 miles in length.
• The upper sources, known as the Ang and Cha streams, rise at elevations of more than 4,900 metres in the T'ang-ku-la Mountains on the southern border of Tsinghai province.
• They flow southeasterly through the Ch'ang-tu (Chamdo) region of Tibet.
• The main stream, known as Lan-ts'ang River, descends in a southerly direction across the highlands of Yunnan.