Whether the northern tribes made the pass difficult to defend by their constant raiding is still debated by scholars, but it is known that the local inhabitants weren't willing to give the Romans free rein over the whole territory.
Scholars are certain that northern tribes made the pass difficult to defend by their constant raiding.
mnli hypothesis: Scholars are certain that northern tribes made the pass difficult to defend by their constant raiding. premise: Whether the northern tribes made the pass difficult to defend by their constant raiding is still debated by scholars, but it is known that the local inhabitants weren't willing to give the Romans free rein over the whole territory.