This paper presented the main background of the reunification of the Crimea and Sevastopol region with the Russian Federation. There is a brief background sample of the contemporary history of Crimea, with special emphasis on the transfers of sovereignty that this region had since the 18th century, until the situation prior to the reunification with the Russian Federation. Subsequently, he will look for the antecedents or immediate causes that first caused independence and then the reunification between the Crimea region and the Russian Federation, sources from both history and geopolitical essays and newspapers of the time, which describe the events, are used. As part of the purpose of this article, a geopolitical study is conducted on the situation in Europe and Eurasia after the collapse of the Union of Soviet Socialist Republics. Among the conclusions it is worth highlighting that the policy of expansion towards the east of Europe of the European Union / NATO block is one of the main factors that triggered the coup in Ukraine in 2014, which is the immediate antecedent of the independence and subsequent process Reunification of Crimea with the Russian Federation.