The terrestrial Neogene sediments are widely exposed along the Ayeyarwady and Chindwin River in central Myanmar and they are divided into three major units: the Freshwater Pegu Beds (Oligocene? to middle Miocene), the Irrawaddy Formation (latest middle Miocene to the early Pleistocene) and the River Terrace deposits (middle to late Pleistocene). A variety of mammalian fossils has been recovered from these sediments and consists of 6 orders, 21 families and 49 genera: Primate (4 genera); Carnivora (4 genera); Artiodactyla (27 genera); Perissodactyla (6 genera) and Proboscidea (8 genera). Myanmar fauna is more similar to the South Asian fauna (Siwalik) than to the East Asian fauna in the Miocene. Faunal interchange between Myanmar and East Asia seems to have started in the late Miocene to the latest Miocene. Faunal interchange among South Asia, East Asia and Myanmar seems to have increased in the early to middle Pleistocene because northern fauna moved southward due to the cooling event in the northern hemispher