The Karen Hills extend to the northwest, separating the Salween and Sittaung River basins.

The ecoregion includes the valley of the Salween River in Kayin, Kayah, and southern Shan states.

The climate is tropical, with warm humid and rainy summers and dry and mild winters.

The climate is influenced by the Southwest monsoon coming from the Bay of Bengal, which brings more rain to the westward-facing mountain slopes.

Larger mammals include tiger (Panthera tigris), Asian elephant (Elephas maximus), gaur (Bos gaurus), banteng (Bos javanicus), wild water buffalo (Bubalus arnee), Asian black bear (Ursus thibetanus), mainland serow (Capricornis milneedwardsii), clouded leopard (Pardofelis nebulosa), Malayan tapir (Tapirus indicus), dhole (Cuon alpinus), Assam macaque (Macaca assamensis), stump-tailed macaque (Macaca arctoides), smooth-coated otter (Lutrogale perspicillata), great Indian civet (Viverra zibetha), and particoloured flying squirrel (Hylopetes alboniger).