The Imperial player is the attack in coexisternce battle. But were does his untis retreat/rout to?

The rules clearly state were defending units can retreat to and that the attacking units stay in their original region but what if that region is the region the coexistence battle is taking place in?

You can retreat to a friendly or neutral or adjacent area, right?

Routing page 31:

If an attacking unit routs, it is removed from the ongoing battle and remains in its origin area, unless that area is already marked with one of the attacker’s routed activation markers, in which case the unit is eliminated.

Retreat page 30:

If the attacker retreats, he does not move any units from their origin areas. All of those origin areas (i.e., those that contain units that were engaged when the retreat was announced) are marked with routed activation markers as described for the defender, above.

End of battle page 30:

If battle ends and no defending units remain in the target area, the attacker may move all, some, or none of his surviving
engaged units and Heroes into the target area. Otherwise, surviving engaged units and Heroes simply remain in their respective origin or target area.

I don't think the target/origin region have to be seperated. So I think the units of the attacker stay in the region after retreat/routing (unless there is already a routed activation Marker in the area, then routing will destroy the unit!)

But wouldn't that allow the Imperial player to "retreat/stop" the coexistence battle as the attacker and stay in the contested region?

Veldrin said:

First, when the Imperial player is the attacker so the traitor is the defender. As the defender the Traitor can choose who will be the active player in the first combat iteration. The rules say that "During every combat iteration other than the first, the active player can retreat" so there have to be at least 2 or 3 rounds of combat iteration (Traitor first - Imperial retreat or Imperial first - Traitor second - Imperial retreat). So there must be a combat and probably some damage for both players units.

If the Imperial Player retreats, his "origin areas (i.e., those that contain units that were engaged when the retreat was announced) are marked with routed activation markers". So yes, I think his units stay in the area but he has to put a routed activation marker there which I think is worst because your units there are blocked much longer than with a normal activation marker.

As I understand things, the routed marker also prevents those units from retreating again until the marker goes away, so any later coexistence battles could hit the Imperials hard.