The Feast
The demon region was simply too large to be searched quickly, even the demons had not been able to find the artifact for the last three days, and it was in a region that was under their control, a region they knew better than the humans did.
Upon coming back, all the team leaders went to the meeting hall to give a report. On the large map that was present in the hall, the areas the team leaders had already been to were marked so that they wouldn't search them again.
Each team leader had a smaller map as well, and the changes made to the big map that was in the hall were visible on their maps, allowing them all to know exactly what places they had searched and where to go next.
It was a very valuable artifact that the humans of the Lumon region had found years ago. The big map was the artifact, but one could create smaller maps and imbue mana to them before connecting them to the big map so that they could see any changes that were made.