Their trade balance was massively negative – it&#x27;s called the &quot;silk road&quot; and not the &quot;Roman wine and glass ware road&quot; for a reason. Gold and silver left Europe and perishable goods were bought for it. It was initially offset by spoils of war and massive mining operations (some of the Roman mines in Spain are still visible today).<p>Apart from that, there was also normal economic and population growth – even without trade, if your population and economy grows, you&#x27;ll need more money if you want to keep prices and wages stable.<p>So, they had several options:<p>• Conquer places that have gold! That went well for a few centuries, until it didn&#x27;t any more.<p>• Debase the currency to make more of the money still here. That was, unsurprisingly, massively unpopular. And because monetary value was still tied to precious metals, people just started to hoard old money to melt it in later (something you still occasionally see with e.g. copper pennies), which led to all sorts of economic problems (occasionally crashing all the way down to barter trade).