Gain a Friendly reputation with the Magram, then speak with Warug.
Desolace is a land at war. The centaurs wage war with each other, and we believe the victor among them will spill out and threaten our strongholds. That, we cannot allow
We must learn how to beat the centaurs, and to do that... we must ally with one of the clans. The Magram centaurs war with the Gelkis. If you fight the Gelkis then the Magram might consider an alliance.
Earn the favor of the Magrams then speak with Warug, in the Magram village in southeastern Desolace.