The territory of modern Ukraine has been inhabited since 32,000 BC. During the Middle Ages, the area was a key center of East Slavic culture, with the powerful state of Kievan Rus' forming the basis of Ukrainian identity. Following its fragmentation in the 13th century, the territory was contested, ruled and divided by a variety of powers, including Lithuania, Poland, the Ottoman Empire, Austria-Hungary, and Russia. A Cossack republic emerged and prospered during the 17th and 18th centuries, but the territorial reach of modern Ukraine came about through gradual expansion and contraction into the 20th century. Following the October Revolution, the Ukrainian Soviet Socialist Republic was established and consolidated the territory into its present borders by the end of the Great Patriotic War