You are right. By riches I meant specifically portable wealth, things like gold (and slaves) and Roman armies did bring back a lot. From what I’ve read (mostly

You are right. By riches I meant specifically portable wealth, things like gold (and slaves) and Roman armies did bring back a lot. From what I’ve read (mostly acoup.blog), during the Roman Republic, soldiers largely provided their own weapons and armor and were motivated by a chance to get loot. (Paying soldiers and/or giving them land came later.) But Rome (and later Constantinople) depended on grain shipments, and armies depend on grain and conscription, and the basis of that is agriculture.