Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Mangde Chhu or Tongsa river flows in central Bhutan traversing roughly north-south. The river rises in Wangdue Phodrang district (or dzongkhag in Dzongkha), near Gangkhar Puensum (Bhutan's highest peak at 7546 m). Bhutan's main east-west highway crosses the Mangde Chhu approximately 8 km west of Trongsa. South of Trongsa, the river drains the eastern slopes of the Black Mountains (Bhutan), and forms the eastern boundaries of Black Mountain National Park and Royal Manas National Park.