The west of the Southern Great Steppe is already allied with Aeryon. The agreement between him and Valgrun has made Valgrun his most reliable ally in the west.
As long as he is not tempted by some short-term benefit, then Valgrun would be his sword to conquer the west.
As for the western border tribes, even though Aeryon himself does not have so many spies to investigate all the western border of the Steppe, he knew that these western border tribes would surely attack the eastern border of Zhou.
When Zhou is strong, they would not attack and defend, when Zhou is weak, the Steppe tribes would attack.
Whether Aeryon gives the order or not, whether he instigates it or not, these western border tribes also knows the logic of attacking the enemy when they are weak
Of course, there could be some miscalculation in his calculations but he is quite sure of this general trend. As long as Zhou shows apparent weakness, the Steppe tribes would pounce on them
