Bubonic plague killed a lot of people in Europe during the Middle Ages, coupled with individual monarchs not being very powerful in comparison to the Roman Empire. Wars in the Middle Ages were often fought by fifes who levied their peasant populations. The ancient world (not just Rome, but also places like Carthage) had large standing armies and slave populations.
Like Marcus Crassus was just some guy who had so much money he privately funded multiple wars. His wealth was unrivaled until you start getting closer to the Renaissance and the Medicis.
Bubonic plague killed a lot of people in Europe during the Middle Ages, coupled with individual monarchs not being very powerful in comparison to the Roman Empire. Wars in the Middle Ages were often fought by fifes who levied their peasant populations. The ancient world (not just Rome, but also places like Carthage) had large standing armies and slave populations.
Like Marcus Crassus was just some guy who had so much money he privately funded multiple wars. His wealth was unrivaled until you start getting closer to the Renaissance and the Medicis.