The China-Russia border is the longest international border in the world, stretching over 4,200 kilometers (about 2,600 miles). It runs from the Mongolian border in the west to the Sea of Japan in the east, passing through various terrains, including mountains, rivers, and forests. This border has significant historical and geopolitical importance, influencing trade and security between the two nations. The border is marked by several key crossings, facilitating trade and travel. Both China and Russia have invested in infrastructure to enhance connectivity, promoting economic cooperation. The region is also home to diverse cultures and communities, reflecting the rich history of interactions between the two countries.