The Russian state expanded into the regions north of today's Mongolia in the 17th century. Much of the line of the today's Mongolia–Russia border line was set by the Treaty of Kyakhta between the Russian and Qing Empires ; however, the treaty left Tuva on the Chinese side of the border. Mongolia's northern border assumed its nearly modern shape in 1911, as Tuva was separated from Mongolia in the breakup of the Qing Empire, and soon became a Russian protectorate. Although an independent Tuvan People's Republic was declared in 1921, this small country became fully annexed into the Soviet Union in 1944, whereupon the former Mongolia–Tuva border became a section of the Mongolia–Soviet border. The latter stayed stable for the rest of the Soviet Union's existence, and continued as the Mongolia–Russia border after the dissolution of the Soviet Union in 1991.
Tripoints
The eastern and western end points of the Mongolia–Russia border are "tripoints", i.e. junctions with the China–Russia border and the China–Mongolia border. A special trilateral agreement, signed on January 27, 1994 in Ulaanbaatar, determines the location of these two "tripoints". The agreement is based on earlier bilateral treaties between the parties involved. The trilateral agreement specifies that a border monument was to be erected at the eastern tripoint, called Tarbagan-Dakh ; a later trilateral protocol determined the tripoint's geographic coordinates as. The border monument and the access roads for it are visible on Google Maps, at approximately ). The trilateral agreement states that no marker will be erected at the western tripoint, which was defined as the peak of the mountain Tavan-Bogdo-Ula, due to its remote and hard to access location, on a mountain covered with eternal snows.
Border crossings
At the border there are ten official crossing points. Two of them are railway crossings, but only one has passenger traffic. Three highway border crossing points are designated as "multilateral", for any passport holders. Another five highway border crossing points are designated as "bilateral", meaning that they are only open to the citizens of the two bordering countries, and not to third-country nationals. The border crossing point near famous Khövsgöl lake is bilateral.
Border violations
According to an article published in 2005, the main problems at the Russian-Mongolian border, specifically in its Republic of Tuva section, were cross-border livestock theft and smuggling of meat.
