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
Indo-Burma Peninsula, the boundary between the two hotspots is represented by the Kangar-Pattani Line, which cuts across the Thailand-Malaysia border, though some analyses indicate that the phytogeographical and zoogeographical transition between the Sundaland and Indo-Burma biotas may lie just to the north of the Isthmus of Kra, associated with a gradual change from wet seasonal evergreen dipterocarp rainforest to mixed moist deciduous forest. Much of Indo-Burma is characterized by distinct seasonal weather patterns. During the northern winter months, dry, cool winds blow from the stable continental Asian high-pressure system, resulting in a dry period under clear skies across much of the