This ecoregion encompasses the Pelly and northern Cassiar Mountains spanning the British Columbia-Yukon border. The mean annual temperature for the area is approximately -3°C with a summer mean of 10.5°C and a winter mean of -17.5°C. Mean annual precipitation is 500-1000 mm, varying with elevation. Boreal forests of white spruce, black spruce, lodgepole pine and aspen cover the lower-elevation valley bottoms. Much of the ecoregion lies above the treeline and is characterized by alpine tundra communities of lichens, dwarf ericaceous shrubs, birch, and willows. Grasses, sedges, cottongrass, and some mosses occupy wet sites. Open-growing black and white spruce, and alpine fir are prevalent in the subalpine region. Some aspen and scrub birch occur in valleys and on lower, warmer slopes of the subalpine sections. Lodgepole pine is common following fires. The Pelly and Cassiar Mountains, composed of crystalline Mesozoic and Palaeozoic strata, are of moderately high relief, ranging from generally over 1500 m asl to the highest peak at 2404 m asl. Relief is greater in the Pelly Mountains than in the Cassiar Mountains. Permafrost is sporadically distributed. Dystric and Eutric Brunisols are codominant in the ecoregion. Dystric Brunisols are associated with coarse igneous rocks at higher elevation. Plateau areas with sandy loam morainal parent materials are associated with Eutric Brunisols. Turbic Cryosolic soils are found in alpine areas and in some imperfectly to poorly drained sites. Representative wildlife includes moose, wolverine, snowshoe hare, black and grizzly bear, Stone's and Dall's sheep, ptarmigan, ground squirrel, and caribou. Land use reflects hunting, trapping, and recreation values as well as mining and mineral exploration activities in both the alpine and subalpine regions. Swift River is the only settlement in the ecoregion. The population of the ecoregion is approximately 30.
This ecoregion is part of the Boreal Cordillera ecozone.