Complex sentence: When the citizens of Pest realized the presence of Cumans in the invading army, mass hysteria emerged, because the townsfolk accused Köten and their Cumans of cooperating with the enemy.
Split into simpler sentences: When the citizens of Pest realized the presence of Cumans in the invading army, mass hysteria emerged. The townsfolk accused Köten and their Cumans of cooperating with the enemy.