Actually it was the expulsion of the native Tartar population combined with the immigration of Russians under Stalin. Russians only became a significant part of the population (28%) in the 1864 census. In the prior census of 1850 they were only 7% of the population. They became a majority in the 1959 census when the Tartars were replaced by Russians under Stalin. In any case, Crimea is not an historically Russian majority province.
When the Orcs took Crimea in 2014, they got rid of the Ukrainians