Ukraine is a country in Eastern Europe. It is the second-largest European country after Russia, which borders it to the east and northeast. It also borders Belarus to the north; Poland, Slovakia, and Hungary to the west; and Romania and Moldova to the southwest; with a coastline along the Black Sea and the Sea of Azov to the south and southeast. Kyiv is the nation's capital and largest city, followed by Kharkiv, Dnipro, and Odesa. Ukraine's official language is Ukrainian; Russian is also widely spoken, especially in the east and south.
During the Middle Ages, Ukraine was the site of early Slavic expansion and the area later became a key centre of East Slavic culture under the state of Kievan Rus', which emerged in the 9th century. The state eventually disintegrated into rival regional powers and was ultimately destroyed by the Mongol invasions of the 13th century. The area was then contested, divided, and ruled by a variety of external powers for the next 600 years, including the Polish–Lithuanian Commonwealth, the Austrian Empire, the Ottoman Empire, and the Tsardom of Russia. The Cossack Hetmanate emerged in central Ukraine in the 17th century, but was partitioned between Russia and Poland, and ultimately absorbed by the Russian Empire. Ukrainian nationalism developed and, following the Russian Revolution in 1917, the short-lived Ukrainian People's Republic was formed.