The Northern Triangle temperate forests occupy the southern slopes of the Namkiu Mountains, the easternmost extension of Himalayas, and extend southeast along the Patkai Range on the border between Myanmar and India, in Kachin State and Sagaing Division of Myanmar, an area that is part of the Golden Triangle.

The mountains run north to south towards the central plain of Myanmar and the forests lie between 1,830–2,700 metres (6,000–8,860 ft) in elevation.

Furthermore the Northern Triangle Temperate forests have been little explored by scientists since the work of Frank Kingdon-Ward in the 1920s and 1930s and their biodiversity is likely underestimated.

The mixed forests lie above 2,100 metres (6,900 ft) in elevation, characterized by broadleaf trees such as oak, magnolia, maple, prunus, holly, and rhododendron, mixed with conifers like picea brachytyla, Himalayan hemlock (tsuga dumosa), Sikkim larch (larix griffithiana), and cypress (taiwania flousiana).

The ecoregion is home to at least a hundred mammals, possibly more, including a number of threatened species such as the Indochinese tiger (Panthera tigris corbetti), the large takin (Budorcas taxicolor), clouded leopard (Neofelis nebulosa), red panda (Ailurus fulgens), Ussuri dhole (Cuon alpinus alpinus), Asiatic black bear (Ursus thibetanus), stump-tailed macaque (Macaca arctoides), capped leaf monkey (Trachypithecus pileatus), red goral (Naemorhedus baileyi), great Indian civet (Viverra zibetha), back-striped weasel (Mustela strigidorsa), Irrawaddy squirrel (Callosciurus pygerythrus), and particolored flying squirrel (Hylopetes alboniger).