Before, Ultar tribe could not easily move some of their reserve forces. Because they fear Aestan tribe would do something.
But now with Brolgadhr tribe taking over the area of Wustkazan tribe, Aestan tribe must think twice before they sent an army against Ultar tribe.
After all, if Kan Aeryon could attack Wustkazan without saying anything, why could he not attack Aestan tribe?
Ultar tribe itself has many settlements and they did not have to do such desperate thing like the Wustkazan tribe and defend one settlement until death.
And even if that is true, actually Yanlan could have retreated. Of course, this is the thought of many chief.
It is easy when it is not you in that situation and circumstances.
The truth is if they were in the same situation and circumstance that Yanlan were in, they probably would make the same choice.
Because the morale of his people would have collapsed back then if he had run away.