The M41, known informally and more commonly as the Pamir Highway is a road traversing the Pamir Mountains through Afghanistan, Uzbekistan, Tajikistan, and Kyrgyzstan in Central Asia. It is the only continuous route through the difficult terrain of the mountains and serves as the main supply route to Tajikistan's Gorno-Badakhshan Autonomous Region. The route has been in use for millennia, as there are a limited number of viable routes through the high Pamir Mountains.