Short answers, pulled from the story.
Kyiv functioned as the capital of Kievan Rus, a polity that united most East Slavic tribes and adopted Byzantine Orthodoxy between the ninth and eleventh centuries. Both Russia and Ukraine claim their heritage from this medieval state ruled by the Varangian Rurikid dynasty.
In 1932, 1933 Ukraine experienced the Holodomor, a man-made famine that killed up to 7.5 million Ukrainians. During the famine known as the Terror-Famine in Ukraine or Famine-Genocide in Ukraine, millions of citizens of the Ukrainian Soviet Socialist Republic died of starvation.
While Ukraine had physical control of the weapons, it did not have operational control because they were dependent on Russian-controlled electronic Permissive Action Links. In 1996 Ukraine transferred all Soviet-era strategic warheads to Russia after signing the 1994 Budapest Memorandum on Security Assurances among the U.S., the U.K., and Russia.
On the 27th of February unmarked soldiers seized important buildings in Crimea including the parliament building and two airports. On the 19th of March 2014 all Ukrainian Armed Forces were withdrawn from Crimea while unmarked soldiers besieged them in their bases.
On the 24th of February 2022 the Russian army invaded Ukraine with ground and air assaults across many parts of the country including on the capital Kyiv. On the 30th of September Putin signed decrees which annexed Donetsk, Luhansk, Zaporizhzhia and Kherson Oblasts of Ukraine into the Russian Federation.