James Paterson in IPA Hey has linked to a map to explain the background to the possibility of civil war in the Ukraine. [Why are civil wars called civil?]. In a nutshell the people in the east relate to Russia and up to 70% speak Russian as their first language. In the west they speak Ukrainain and they relate more to Europe. Recall that much of the Ukraine was a part of the Austro Hungarian empire. Ludwig von Mises and many other people who achieved fame in Vienna and other European cities were born in the Ukraine.
Ukrainian is the majority and official language of Ukraine. But, as a legacy of of the country’s subjugation by Russia, many Ukrainians speak Russian, which is the native language for about one-third of the population. The Russian speakers are clustered in the south and east. A significant chunk of them are ethnic Russian, as well. In some regions, more than three-quarters of the population speaks Russian as their primary language.
Heavily Russian-speaking regions can tend to be more sympathetic (or at least less hostile) to policies that bring their country closer to Russia, as Yanukovych has been doing. But the Ukrainian-speaking regions have historically sought a Ukrainian national identity that is less Russia-facing and more European. So this is about politics, yes, but it’s also about identity, about the question of what it means to be Ukrainian.
Ukraine’s ethno-lingistic political division is sort of like the United States’ “red America” and “blue America” divide, but in many ways much deeper — imagine if red and blue America literally spoke different languages.