It could explain it if you consider how it upended stable equilibriums. If the sedentary civilizations had developed defenses against horse-riding nomads with a specific allocation of resources to that effort, and there was a sudden increase in the size of the threat vector emanating from these horse-riding nomads, it could throw their strategic posture out of alignment with their strategic needs.
In terms of numbers, it's entirely possible that larger numbers of defending sedentary soldiers are needed than attacking horse-riding nomad soldiers for the former to mount an effective defense against the latter.
ETH_start|1 year ago
In terms of numbers, it's entirely possible that larger numbers of defending sedentary soldiers are needed than attacking horse-riding nomad soldiers for the former to mount an effective defense against the latter.