Kazimir Erso's so-called "encouragement" was not just a matter of thought.
He had truly put it into action.
A detachment of the fleet carrying a company of interstellar warriors was on its way to the Seven Horse Territory.
Going directly was certainly impossible; the route was blockaded by Green Skins. To get to the Seven Horse Territory, one would have to take quite a detour.
In this sense, it couldn't really be said the two sides were completely cut off from each other, since the southern and eastern regions belonging to two other star domains were still Imperial territory.
But how are star domains delineated?
In the True Universe, the physical distance between different star systems is incredibly vast, and for human ships that can at most perform sub-light-speed travel, such distances are not traversable. Only by relying on Star Realm Tunnels to warp can one cross the astronomical distances of the physical universe.