The M41, known informally and more commonly as the Pamir Highway (), is a road traversing the Pamir Mountains through Afghanistan, Uzbekistan, Tajikistan and Kyrgyzstan with a length of over 1,200 km. It is the only continuous route through the difficult terrain of the mountains and is 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. The road formed one link of the ancient Silk Road trade route. M41 is the Soviet road number, but it only remains as an official designation in post-Soviet Uzbekistan, as confirmed by official decree. Kyrgyzstan and Tajikistan have passed decrees abolishing Soviet numbering of highways and assigning their own national numbering. Route description Sources disagree on the termini of the highway, with Mazari Sharif, Afghanistan; Termiz, Uzbekistan; Dushanbe, Tajikistan; and Khorog, Tajikistan all being offered as the beginning of the highway. All sources, however, agree that the highway ends in Osh, Kyrgyzstan. Today, the route is part of the M41 highway, which starts at Termiz at and ends at Kara-Balta to the west of Bishkek, Kyrgyzstan at . The route passes northward through Termiz before turning east and crossing into Tajikistan. It then follows a general eastward route through Dushanbe, the capital of Tajikistan, to Khorog, crossing the Kafirnigan, Vakhsh, and Bartang Rivers. From there, it continues east for about 310 kilometers to Murghab, where it crosses the Murghab River. The highway then passes through the 4,655-meter (15,270 ft) high Ak-Baital Pass and past Lake Karakul before crossing into Kyrgyzstan to its terminus in Osh. The road was constructed partly in the end of 19th century (during The Great Game), and mostly in 1930s by the Soviet Union. In 2000s Pamir Highway was connected with China and Karakoram Highway. The Pamir Highway is designated as route M-41 over much of its length in Tajikistan and Kyrgyzstan, and is known as the second highest altitude international highway in the world (4,655 m). The section between Dushanbe and Murghab has the European route number E 008. The section between Sary-Tash and Osh, Kyrgyzstan has the European route number E 007. Construction and maintenance levels vary substantially along the highway. The roadway is unpaved in some areas, but otherwise paved most of the way. Except for its stretches in Kyrgyzstan and nearing Dushanbe, the road