How was trade able to flourish before Rome fell?

As explained below.

Explanation:

The fall of Rome happened in the early September and affected European societies as the roman empire were at the center of the trade, military, and food. Before the fall the Byzantine was known as the most robust economies of the Mediterranean due to its prime trading network as it had a monopoly on issuing coins. Many of the western advances were adopted by the Byzantine such as the windmills. Gain and silk were the two main commodities of the empire. Trade-in slaves and textile took place and the emperor was strictly controlled by the internal circulation of commodities.