FTP name this largest river of northern Vietnam, along which lies Haiphong and Hanoi.
Locally called the Song Hong, it arises is the central Yunnan province, and is joined by the Song Li and Song Da (or Clear and Dark Rivers) on its way to the sea.  Its common name derives from the large amount of silt it contains, which is deposited in a densely populated 2,700-square-mile delta on the Gulf of Tonkin.  FTP name this largest river of northern Vietnam, along which lies Haiphong and Hanoi.
Locally called the Song Hong, it arises is the central Yunnan province, and is joined by the Song Li and Song Da (or Clear and Dark Rivers) on its way to the sea.  
the Red River or Yuan Chiang