In many ways a continent away from the folkloric west of Ukraine, the predominantly Russian-speaking territory east of the Dnipro River is often dismissed as 'not Ukrainian enough'. But, from an economic and political standpoint, this vast region is the country's power source.
The region was hit hardest by the crisis precipitated by the 2014 revolution. A part of it (fortunately not a very big one) has been occupied by Russian-backed rebels who proclaimed two 'people's republics', putting Donetsk and Luhansk on the front line of a simmering conflict. We can't overemphasise the danger of coming anywhere close to rebel-held areas.
That said, the rest of eastern Ukraine is safe to travel in, provided that you watch the news. The area includes places that are key to understanding Ukraine, such as the Zaporizhska Sich, Gogol’s Poltava region and Unesco-listed Chernihiv. Kharkiv and Dnipro are large industrial cities with intriguing cultural dynamics.