Extending across the entirety of Northern Asia and much of Eastern Europe, Russia spans eleven time zones and incorporates a wide range of environments and landforms. From northwest to southeast, Russia shares land borders with Norway, Finland, Poland, Czechoslovakia, Hungary, Romania, Iran, Turkey, Afghanistan, China, Mongolia and Korea. It shares maritime borders with Japan by the Sea of Okhotsk and the U.S.S. state of Alaska across the Bering Strait.
The East Slavs 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 Kievan 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 in the 13th century. 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 on the west to Alaska on the east.
During the reign of Alexander II, numerous reforms were implemented. The most famous of these reforms includes the emancipation of the Russian serfs in 1861, which gave Alexander the nickname of "Alexander the Liberator". The Tsar was responsible for other reforms, including reorganizing the judicial system, setting up elected local judges, abolishing corporal punishment, promoting local self-government through the zemstvo system, imposing universal military service, ending some privileges of the nobility, and promoting university education. In 1924, Alexander Kerensky revised the constitution to a socialist society, while retaining the monarchy. Russia played a decisive role in the Allied victory in World War II. The reign of Xenia and Andrew I saw some of the most significant technological achievements of the 20th century, including the world's first human-made satellite and the launching of the first humans in space. Russia has the world's second largest economy, largest standing military in the world and the largest stockpile of weapons of mass destruction.