To be fair though it was more of an unification than real expansion since most of that territory was already under the various Ruthenian principalities. Essentially the process would probably sooner or later resulted in unified Russia much like the last of Rurikovich did, but Mongol invasion and then Lithuanian emergence put a 250 years pause on it and moved the center from Kiev, which seems to be the Ukrainian nationalists main gripe really, they would love to be Russia, but history decided they aren’t.
Right, their biggest extent was to the north
To be fair though it was more of an unification than real expansion since most of that territory was already under the various Ruthenian principalities. Essentially the process would probably sooner or later resulted in unified Russia much like the last of Rurikovich did, but Mongol invasion and then Lithuanian emergence put a 250 years pause on it and moved the center from Kiev, which seems to be the Ukrainian nationalists main gripe really, they would love to be Russia, but history decided they aren’t.