Mongolia–Russia border

The Mongolia–Russia border (Mongolian: Монгол-Оросын хил, romanized: Mongol-Orosiin hil, [ˈmɔɴɢɞ̆ɮ ɔɾɞ̆ˈsiŋ çɪɮ]; Russian: Российско-монгольская граница, romanized: Rossijsko-mongoljskaja granica) is the international border between Mongolia and the Russian Federation. It runs from west to east between the two tripoints with China for 3,452 km (2,145 mi). The boundary is the third longest border between Russia and another country, behind the Kazakhstan–Russia border and the China–Russia border.