Russia (officially the Russian Federation), is a country in northern Eurasia. It is a federal semi-presidential republic. At 17,075,400 square kilometres, Russia is the largest country in the world, covering more than one-eighth of the Earth's inhabited land area. Russia is also the world's ninth most populous nation with nearly 144 million people as of 2015.
Extending across the entirety of northern Asia and much of Eastern Europe, Russia spans nine time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Finland, Estonia, Latvia, Lithuania and Poland (both with Kaliningrad Oblast), Belarus, Ukraine, Georgia, Azerbaijan, Kazakhstan, China, Mongolia, and North Korea. It shares maritime borders with Japan by the Sea of Okhotsk and the U.S. state of Alaska across the Bering Strait.
The nation's history began with that of the East Slavs, who emerged as a recognizable group in Europe between the 3rd and 8th centuries AD. Founded and ruled by a Varangian warrior elite and their descendants, the medieval state of Rus arose in the 9th century. In 988 it adopted Orthodox Christianity from the Byzantine Empire, beginning the synthesis of Byzantine and Slavic cultures that defined Russian culture for the next millennium. Rus' ultimately disintegrated into a number of smaller states; most of the Rus' lands were overrun by the Mongol invasion and became tributaries of the nomadic Golden Horde. The Grand Duchy of Moscow gradually reunified the surrounding Russian principalities, achieved independence from the Golden Horde, and came to dominate the cultural and political legacy of Kievan Rus'. By the 18th century, the nation had greatly expanded through conquest, annexation, and exploration to become the Russian Empire, which was the third largest empire in history, stretching from Poland in Europe to Alaska in North America.
Following the Russian Revolution, the Russian Soviet Federative Socialist Republic became the largest and leading constituent of the Soviet Union, the world's first constitutionally socialist state and a recognized superpower, which played a decisive role in the Allied victory in World War II. The Soviet era saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite, and the first man in space. Following the dissolution of the Soviet Union in 1991, the Russian SFSR reconstituted itself as the Russian Federation and is recognized as the continuing legal personality (the sole successor state) of the Union state.