Russia, officially the Empire of Russia, is a country in northern Eurasia. It is a federal parliamentary constitutional monarchy. From northwest to southeast, Russia shares land borders with Sweden, Poland, Ukraine, Crimea, Caucasia, Turkestan, Mongolia, and Manchuria. It shares maritime borders with Japan and Alaska across the Bering Strait. At 16,XXX,XXX sq km (6,XXX,XXX sq mi), 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.
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 Atlantis.
Following the Russian Revolution, the reformed empire was one of the world's recognized superpowers, which played a decisive role in the Allied victory in the Second Great War. The modern era has seen 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. With the United States, Russia also landed the first man on the moon.
The Russian economy ranks as the ninth largest by nominal GDP and sixth largest by purchasing power parity in 2014. Russia's extensive mineral and energy resources, the largest reserves in the world, have made it one of the largest producers of oil and natural gas globally. The country is one of the seven recognized nuclear weapons states and possesses the third-largest stockpile of weapons of mass destruction. Russia is a great power and a permanent member of the International League Security Council, a member of the G20, the Council of Europe, the Pacific-Asian Treaty Organization, the Shanghai Cooperation Organization, the Eurasian Economic Community, the Organization for Security and Cooperation in Europe (OSCE), and the World Trade Organization (WTO), as well as being the leading member of the Commonwealth of Independent States.