While Crimea has a majority of Russian speakers, there are also sizable minorities of Ukrainians and Crimean Tatars.
According to the BBC, Crimea came under the control of a Tatar Khanate in 1443, after centuries of Greek and Roman influence. It eventually came under Ottoman control and remained there until it was annexed by the Russian empire under Catherine the Great in 1783, the same year that part of the Russian fleet was stationed at the port of Sevastopol.
During the Crimean War in the 1850s, Britain and France sent troops to Crimea to combat what they saw as Russian imperialistic ambition. Crimea was occupied by the Nazis during World War II; when it came under Soviet control, Stalin expelled Crimean Tatars, saying they were Nazi collaborators. They were sent to Central Asia and Siberia, where many died. In 1954, Russia handed over control of Crimea to Ukraine.
Sources: BBC, The Wilson Center
Putin's government has a history of engaging with right-wing nationalist groups in Russia. While the nationalism displayed by the Night Wolves isn't new, rights groups say Putin has harnessed it to support his imperialistic tendencies, maintain his grip on power, and oppress minority groups like LGBT Russians, ethnic minorities, and political dissidents.