Historically, the 4 oblasts were Russian. That's why the majority living there are ethnically Russian, they speak Russian as their primary language. They have ties to the land. It wasn't until Lenin gave Ukraine in 1922 the oblasts that these territories came under Ukrainian jurisdiction, but at a national level this area is traditionally, culturally, and ethnically Russian. That's why they seceded from Ukraine, and later asked to be annexed. It's the land of their ancestors, and their ancestors were Russian.