The Crimean Peninsula (Crimean Tatar: Къырым ярымадасы, Qırım yarımadası; Ukrainian: Кри́мський піво́стрів; Russian: Кры́мский полуо́стров), also known simply as Crimea (/kraɪˈmiːə/; Crimean Tatar: Къырым, Qırım; Ukrainian: Крим; Russian: Крым), is a major land mass on the northern coast of the Black Sea that is almost completely surrounded by both the Black Sea and the smaller Sea of Azov to the northeast. The peninsula is located south of the Ukrainian region of Kherson and west of the Russian region of Kuban. It is connected to Kherson Oblast by the Isthmus of Perekop and is separated from Kuban by the Strait of Kerch. The Arabat Spit is located to the northeast, a narrow strip of land that separates a system of lagoons named Sivash from the Sea of Azov.
Crimea (or the Tauric Peninsula, as it was called from antiquity until the early modern period) has historically been at the boundary between the classical world and the Pontic–Caspian steppe. Its southern fringe was colonised by the ancient Greeks, the ancient Romans, the Byzantine Empire, the Crimean Goths, the Genoese and the Ottoman Empire, while at the same time its interior was occupied by a changing cast of invading steppe nomads, such as the Cimmerians, Scythians, Sarmatians, Goths, Alans, Bulgars, Huns, Khazars, Kipchaks, and the Golden Horde. Crimea and adjacent territories were united in the Crimean Khanate during the 15th to 18th century.
In 1783, Crimea was annexed by the Russian Empire. Following the Russian Revolution of 1917, Crimea became an autonomous republic within the Russian Soviet Federative Socialist Republic in the USSR, though later, during World War Two, it was downgraded to the Crimean Oblast.
In 1954, the Crimean Oblast was transferred to the Ukrainian Soviet Socialist Republic, by Nikita Khrushchev in order to bolster the "unity of Russians and Ukrainians" and the "great and indissoluble friendship" between the two peoples. It became the Autonomous Republic of Crimea within newly independent Ukraine in 1991, with Sevastopol having its own administration, within Ukraine but outside of the Autonomous Republic.
Since 1997, after the Peace and Friendship Treaty signed by Russia and Ukraine, Crimea hosts the Russian Black Sea Fleet naval base in Sevastopol. The ex-Soviet Black Sea Fleet and its facilities were divided between Russia's Black Sea Fleet and the Ukrainian Naval Forces. The two navies co-used some of the city's harbours and piers, while others were demilitarised or used by either country. Sevastopol remained the location of the Russian Black Sea Fleet headquarters with the Ukrainian Naval Forces Headquarters also based in the city. On April 27, 2010, Russia and Ukraine ratified the Russian Ukrainian Naval Base for Gas treaty, extending the Russian Navy's lease of Crimean facilities for 25 years after 2017 (through 2042) with an option to prolong the lease in 5-year extensions.
In March 2014, following the ousting of the Ukrainian president in the 2014 Ukrainian revolution and the subsequent takeover of the region by pro-Russian separatists and Russian special forces, local authorities held a referendum on "reunification with Russia", the official result of which was a large majority in support. The Russian Federation then officially annexed Crimea and now administers it as two federal subjects: the Republic of Crimea and the federal city of Sevastopol. Ukraine does not recognise the annexation and, backed by most of the international community, continues to assert its right over the peninsula.