since Yaroslav is in my ancestry tree. It doesn't say what state, just the leader of Kyiv.
His name is not written like this in my tree, Ярослав instead its in old Norse like this Jarisleif.
He most doubtedly was of leader of the Kyivan Rus state.
In the late 1700s the term Ruthenia was used as modern day Ukraine.
that term changed in the 1840s from Little Rus to Ukraine. But the term was still used in the Austro-hungarian empire until it colapsed.
Regional Ukrainians still used the term ruthenian in parts of the old Austro-hungarian empire. Now mostly Carpatho-rusyns use it. Lemkos, Hutsuls, Boikos. They are Ukrainian as we stem from one of the seven Ukrainian tribe.