The Fleabirds are a group of people indigenous to North America who have rejected the collectivism and sedentary lifestyle inherent in the Cosmic Era. Rather than living in the gleaming arcologies, steaming geofronts, or the great heaps of the urban rims and favelas. Rather, they live in caravans that travel the countryside of the continent.
A revolt or attack happens against a strong city/kingdom. All the losers of the battle that can be captured are brutally crucified along the roads that enter the kingdom to show their strength and as a demonstration of what happens to their enemies.