Creating new states from territory that nominally belonged to an existing state (in the sense of claiming everything west of their established territory) but was actually unexplored frontier was a little different than carving a chunk out of an existing state with fully-established borders after the fact.
Creating new states from territory that nominally belonged to an existing state (in the sense of claiming everything west of their established territory) but was actually unexplored frontier was a little different than carving a chunk out of an existing state with fully-established borders after the fact.
No doubt it’s a bit different. But it was still splitting and both did have established western boundaries.