Short answers, pulled from the story.
The 1992 battle of Bender turned the Dniester river into a blood-soaked boundary in June 1992. Russian military intervention secured victory for separatists who had declared Transnistrian independence months earlier.
President Medvedev signed decrees on the 26th of August 2008 recognizing Abkhazia and South Ossetia as sovereign states following the Russo-Georgian War. Georgian security forces deployed along demarcation lines with Georgia shortly after these diplomatic moves.
Russian armed forces occupy parts of Donetsk Oblast, Kharkiv Oblast, Kherson Oblast, Luhansk Oblast, Mykolaiv Oblast, Zaporizhzhia Oblast, and all of Crimea. Ukrainian president Volodymyr Zelenskyy designated the 20th of February 2014 as the official start date of temporary occupation by Russian forces.
Vladimir Putin ordered forces to perform peacekeeping functions on the 22nd of February before beginning a special military operation on the 24th of February 2022. This invasion made it illegal within Russia to refer to the conflict as a war despite its scale being the largest European conflict since World War II.
The Georgian parliament unanimously passed a resolution on the 28th of August 2008 declaring both regions as Russian-occupied territories under international law. That same law forbids entry into the regions from Russia and subjects violators to fines or imprisonment.