In the violence and chaos of the past week, the question has been raised whether stability might be served by dividing Ukraine, Czechoslovakia-style, into a Ukrainian-speaking northwest and a Russian-speaking southeast?

It’s not that simple. While Ukraine does have linguistic, cultural and religious divisions, the dividing lines are far from clear. Yes, there are western provinces that were once under Hapsburg rule where Ukrainian nationalism runs strong, and Russians in Crimea who are not reconciled to being part of Ukraine and are now demonstrating against the changes in Kiev. But, in the rest of the country of 46 million people, languages, ethnic identities and loyalties are mixed and muddled.

Ukrainian and Russian are related languages, and the populations have mixed over centuries through intermarriage. In that respect, President Vladimir Putin of Russia is right in describing Ukrainians as kin; where he is wrong is in presuming that even the 30 percent of Ukrainians who list Russian as their mother tongue want to rejoin his Russian Federation.

On my last extended visit to Kiev in May 2010, I met with a group of Russian-speaking journalists (two-thirds of Ukraine’s newspapers are in Russian), and none of them yearned to go back under Moscow rule. “Our hope is to make Ukraine into what Russia should have become, a liberal, tolerant democracy,” one journalist told me. That idea seems to hold sway among many younger, educated, Russian-speaking Ukrainians, many of whom supported the protest movement to oust President Viktor Yanukovych.

“Dividing Ukraine is a nonstarter because there is no sharp division, no sharp demand for separation,” explained Keith Darden, a professor at the American University School of International Service who studies national loyalties and state-building in Eurasia.

The trouble is that the uprising in Independence Square drew a disproportionate number of demonstrators from the western provinces with the strongest tradition of nationalism. Among the identified victims, Mr. Darden noted, 50 percent were from those regions, and the nationalists now believe they have a claim on power.

That has raised fears among many Russian speakers in the east and south that Ukrainian nationalists will dominate the next government, a fear fanned by Parliament’s quick vote after Mr. Yanukovych fled to overturn a 2012 law that gave Russian (or any other language) the status of an official language in cities or regions where 10 percent or more spoke it. Russia has also fueled fears by portraying the opposition as extremists and now by holding military exercises near the Ukrainian border.

“The problem here is what actually started as a kind of pro-European, pro-democratic set of demonstrations is very quickly becoming ethnicized,” said Charles King, an expert on post-Soviet politics at Georgetown University. “This is a problem for Ukraine, for Europe, for Russia, for the United States.”

And this is a challenge the interim government now being formed must address quickly, first by ensuring that it represents all parts of the Ukrainian population; second by confirming the territorial unity of Ukraine; and third by getting state institutions functioning again. “Ethnic conflicts thrive on moments when the state seems weak,” said Mr. King, noting that vigilantes with clubs are standing guard at some government buildings in Kiev.

The new government would do well to remember that the uprising began as an outcry against rampant corruption and a longing to move closer to European values and institutions — not as a call to impose one vision of Ukraine on all its disparate citizens.