The Northern Beastmen indeed discovered this new human force. Previously inaccessible highlands could now be entered.
For the Beastmen, having a new area to expand into was naturally a cause for celebration. All other areas had been sealed off, making it impossible for them to pass through; this new direction might just be a turning point.
But suddenly, the Beastmen realized that these humans seemed different from the ones before.
These humans had fallen. They fraternized with the Undead, with a host of Undead Creatures escorting them.
Therefore, the Beastmen dared not act rashly, having no idea what might come down from the highlands. Beastman warbands continuously probed the area, gradually converging towards this new zone.
Since they were not professional soldiers, it was impossible for them to assemble from the start, or else they would be unable to survive.
