Crossing the Sicarl Mountain and entering Carsonrick from Draleon, there were certainly more than one mountain road, but Rising Wind Trail was the most accessible by carriage and also the easiest route to travel.
Even in the era when the steam train had reached the mouth of Sicarl Mountain, this ancient mountain road remained the most important trade route in the surrounding area.
Rising Wind Trail wound up Sicarl Mountain and eventually, after crossing the border, led to a foreign city on the other side of the mountains. Red Water Camp was the largest outpost and military camp established by the Draleon Royal Army in the border area. It served both defensive and reconnaissance duties, and in conjunction, with the checkpoints and tax officers, managed the issues of goods entering and leaving the country.
Of course, there were other military camps in the Sicarl Mountain besides Red Water Camp, but those were not known by ordinary people.