The ties binding the two countries form a complex weave — personal, historical, religious, geographical — that stretches back more than a millennium. Timothy Snyder, a professor of history at Yale University, argues that much of the history was manipulated in modern times to create links where none existed. But myths endure.

The Russian Orthodox Church traces its origins to mass conversions purportedly forced by Vladimir, the grand prince of Kiev, in 988. The name Russia, adopted by Peter the Great for the empire in the early 18th century, was rooted in Kievan Rus, a medieval state that included lands that became Ukraine.

“They stole our church; they stole our name,” said Andrii Bychenko, who runs the sociology program at the Razumkov Center, a think tank here.