What is the connection between the fall of the Soviet Union and the outbreak of ethnic conflicts in Russia and the Republics

Well, the Soviet Union was made from different countries in Eastern Europe - many of them containing totally different ethnic populations, and whole other countries after the communism comes change their status as territory of Russia. After the fall of the Soviet Union many of the Republics regain their sovereignty, but then there is the question with territories which previous changed their status to stay part of Russia, to become part of the neighboring countries or to exist independently. This caused a lot of ethnic problems and wars. For example in Ukraine a lot of people speak Russian and prefer again to be part of Russia. Also there are a lot of Bulgarians in Ukraine, which makes whole cities to be renamed and the official language there to be strictly Bulgarian. In Moldova, the problem is Rumanian or Russian and usually because of these ethnic problems some of the Eastern European countries are bilingual.