River systems of Thailand divides into two major branches, the " Tiền Giang" (Front River) and "Hậu Giang" (Back River). These in turn enter the South China Sea through nine estuaries. The following are the principal tributaries of Mekong River which flow through Thailand (tributaries entirely outside the Thai border not shown). The Mekong drains a considerable portion of northeast Thailand. In terms of Thai territory drained, it is second only to the Chao Phraya system. The Salawin River rises in Tibet (Tibetan: རྒྱལ་མོ་རྔུལ་ཆུ།) after which it flows through Yunnan, where it is known as the "Nujiang" River (), although either name can be
Geology of Myanmar India and the Eurasia Plate led to the formation of the Himalayan Orogeny. On the eastern margin of the India plate, high oblique subduction occurs between the boundary of India and the Burma-micro plate. Between late Eocene to Miocene, the Burma and Shan-Thai block rotated 30° to 40° clockwise, to accommodate the major collision along the plate boundary. This resulted in the trend of arc shifting from east-west to the north-south direction. The subduction boundary forms an accretionary prism and eventually with thrusting and folding forms the Indo-Burma Range. In late Miocene to Pliocene, the slab detachment of Burma-microplate beneath