You are one of those low information folk we keep hearing about right? You follow Zerohedge correct?
No one sane is believing that. This "referendum" was recognized only by 10 countries other than Russia in the UN - Armenia, Belarus, Bolivia, Cuba, North Korea, Nicaragua, Sudan, Syria, Venezuela, and Zimbabwe. No one else.
From Wiki
The modern history of Crimea begins with the annexation by the Russian Empire in 1783. In 1921 the Crimean Autonomous Soviet Socialist Republic was created. This republic was dissolved in 1945, and the Crimea became a province first of the Russian SSR (1945-1954) and then the Ukrainian SSR (1954-1991). Since 1991 it has had the status of an Autonomous Republic within Ukraine until its annexation by the Russian Federation in the 2014.
Russia has an important naval base in the Crimea at Sevastopol, From the Finacal Times
"The Crimean port of Sevastopol, home of the Black Sea fleet, is vital to Russias naval power in the Mediterranean and beyond. As such the base is of critical importance as Russia seeks to regain some of the global clout that has been dwindling since the disintegration of the Soviet empire."
Sevastopol was built by Catherine the Great in 1784. The Crimea was "given" to the Ukraine as a house keeping arrangement while both where part of the Soviet Union. Now that the Soviet Union is gone Russia and rightly so IMHO, wants the Crimea back. The Ukraine has no historical claim to it, it's been Russian since the time of Catherine the Great.