Zhou Tian's subordinates may still be beastmen, but at that time, the power in his hands was, in fact, no longer the traditional Beastman Empire.
Beastmen generally give the impression of being simple and warlike, with underdeveloped brains. How they live on a daily basis doesn't matter; what matters is that in wartime, beastmen mostly rely on their strong close combat abilities. As for other tactics, beastmen hardly have many. Relying on their large numbers and superior close combat abilities, beastmen, who originally lacked the power for large-scale destruction, were still able to defeat many races with magic and other forms of power.
It could be said that beastmen have always been synonymous with brawn over brain. If one knew the details of the beastmen, making targeted preparations, dealing with beastmen wouldn't be a difficult task for any person or power.