The troops were separated from the main army and had to march through one of the corners of the dungeon to complete their ritual scouting session. Jake chose this region for three reasons. The first one was its distance from the main settlement. Eliminating them would give rise to two incredible opportunities. Distance ensured that the squad was expected to take a long time to return, which gave the perfect window to ambush more units. The second opportunity is the information they would be able to gather from the corpses.
They will be able to get some extra equipment and, if possible, some maps or schedules that would help them define more targets. The second reason behind choosing the region was how isolated and hidden it was. The terrain was disorienting, making it difficult for Kobold troops to march here. Since it was difficult to come in, it would be difficult to move out.