There are few documents to explain how a system of coinages developed and operated across the Roman Empire, but the coins themselves and their find contexts, where published and correctly interpreted, can show how a system developed under Julius Caesar and Augustus became dominant quickly over the western provinces and incrementally over the East. The center controlled the issue of gold and silver but allowed leeway to provincial mints to produce silver of eastern denominations and to cities to mint low value fiduciary bronze coins. After the political and economic changes of the mid-third century led to mistrust of silver-alloy coinages, the civic bronze that depended on it disappeared, and new systems that were meant to cover the entire empire were introduced after 275 ce .