Backgrounder: Timeline of major events in Crimea

BEIJING - Crimea, a southern Ukrainian autonomous republic, will hold a referendum Sunday on whether to stay with Ukraine or become part of Russia.

The following is a timeline of major events in Crimea's history and its recent crisis:

Crimea has a history of more than 2,000 years. The territory has been conquered and controlled many times.

18th-20th centuries - Controlled by the Russian Empire;

1922-1991 - Part of the Soviet Union, first with the Russian Soviet Federative Socialist Republic and then with the Ukrainian Soviet Socialist Republic (on Feb 19, 1954, the presidium of the Supreme Soviet of the USSR decided to transfer Crimea to Ukraine with a decree which pointed to "the commonality of the economy, the proximity, and close economic and cultural relations between the Crimean region and the Ukrainian SSR" );

1991 - Part of a newly independent Ukraine as the Republic of Crimea;

1992 - Yalta Agreement to divide the Soviet Black Sea Fleet;

1992 - The Crimean Supreme Council declared independence on May 5 pending a referendum planned for later that year; the Ukrainian parliament ruled the declaration illegal and gave the Crimean Supreme Council a deadline of May 20 to rescind its declaration, which the council did;

1993 - The Crimean parliament called for creation of a presidential post for the autonomous republic;

1994 - Russia, the United States and Britain signed in Hungarian capital Budapest a memorandum on security assurances regarding Ukraine's accession to the Treaty on the Non-Proliferation of Nuclear Weapons; Ukraine gave up the world's third largest nuclear weapons stockpile between 1994 and 1996;

1997 - The Treaty of Friendship, Cooperation and Partnership on the division of the Black Sea Fleet signed, with Russia getting 80 percent of the fleet and a 20-year lease on facilities in the Crimean port of Sevastopol;

1998 - New Ukrainian constitution changed the name of Crimea to the Autonomous Republic of Crimea, but Ukrainian parliament retained a right to veto any legislation passed by the Crimean parliament;

2001 - A census showed 58.5 percent of Crimea's population were ethnic Russians, with ethnic Ukrainians and Crimean Tatars accounting for 24.4 percent and 12.1 percent, respectively;

2006 - Anti-NATO protest against the participation of NATO marines in the Sea Breeze 2006 Ukrainian-NATO drill;

2009 - Ukraine Security Service started criminal proceedings against a pro-Russian association, People's Front Sevastopol-Crimea-Russia;

2010 - Ukrainian parliament approved the extension of the Sevastopol lease to 2042;

Feb 22, 2014 - Ukrainian President Viktor Yanukovych removed from office;

Feb 26, 2014 - Pro-Russia and pro-Ukraine protesters clashed in front of the Crimean parliament building in Simferopol and pro-Russia protesters sought for assistance from Russia;

March 1, 2014 - Russian parliament granted Russian President Vladimir Putin the authority to use military force in Ukraine;

March 6, 2014 - Crimean parliament voted in favor of joining Russia in the form of a union between the two nations.