At first, the NPC forces took the Monster Force right next to them quite seriously. Especially since inside their ranks there was an NPC faction that had almost been annihilated by Zhou Tian, if not for unfavorable circumstances, they probably would have fought with Zhou Tian at that time.
However, when Zhou Tian had wasted hundreds of years, during which his Beastmen had no strength to do anything significant, those NPCs gradually began to forget the threat posed by Zhou Tian and his enemies.
Having not seen any actions from Zhou Tian's Beastmen for hundreds of years, those NPCs began to believe that Zhou Tian's forces were no threat at all. Even if there would come a day when Zhou Tian would fight with them, at least for the time being, it seemed Zhou Tian was not likely to easily start a war with them.