When the new group of powerful people called Achalanata appeared it was not only the humans who were shaken, the beasts were also the same. Actually they were more shaken as they were the eternal enemy of humanity. So this new group of powerful people was an immediate threat to them. For that reason they felt the necessity of taking immediate steps against this problem.
The beasts were dominating the humans little by little. So they were confident in gaining a significant advantage after a few more years. But the arrival of this new group had immediately destroyed their advantage and now the humans were once again equally matched against them. No, objectively, the humans now held a considerable advantage.