Unfortunately all countries in Eastern were not recently dominant powers in Eastern Europe except the Soviet Union. So many new countries have been created recently that it can be said that all of these were not dominant powers. Problem with question is that in past almost all countries in Eastern Europe were part of or carried name of once dominant powers. Examples are the countries that once were part of one of the world's empires, especially the Holy Roman Empire, the Russian empire, the Ottoman empire, Sweden, Austrian-Hungarian empire, the Roman empire, France under Napoleon, the Byzantine empire (lands held in lower Eastern Europe), the Greek empire, or farther back, the Macedonian Empire or the Minoan Empire (the actual extent of which is still not clear). Therefore this question is basically unanswerable unless the definitions within the question are clarified/defined (especially as to what does dominant mean, what time frame is being discussed, and what area constitutes "Eastern Europe".
Italy
Chile was not one of the dominant powers.
who became the dominant people of southern eastern europe
Christianity
Christianity
In order to answer this we need to see a list of countries.
Carpathian Mountains
Europe was the center of world power.
they are the Carpathian Mountains
well, it had its high and lows depending on the date, and it was no doubt a very powerful nation empire when joined up with hungary- and i do believe, using my background knowledge, yes, it was a dominant power of eastern europe
the emergence of the US and the USSR as the dominant world powers, supplanting the UK and the other nations of Europe; the division of Germany into East and West; Soviet occupation of Eastern Europe; the end of fascism is a significant political force; (indirectly) the establishment of a Jewish state in Palestine
Before 1991, Eastern Europe was under Soviet influence. After that time, there has been a slow recovery to Westernized influences.