City-states trade with Beastman tribes for crystals.
Beastmen use crystals to summon their deities.
-As tension with Garlemalde increases (Garlemalde has basically sworn genocide on Beastman tribes) Beastmen are hoarding their crystals to help defend against Garlemalde.
City-states need crystals for production, so they are more aggressively trying to acquire crystals from Beastmen.
As the Garlean threat becomes more pronounced the tension between the City-states and the Beastmen increases as both try to prepare defenses for the impending invasion.