Solidus - Justinian I VICTORIA AVGGG, Constantinopolis

Justinian I's reign saw the solidus function as the dominant trade currency across the Mediterranean world, circulating far beyond Byzantine borders into Persia, Arabia, and sub-Saharan Africa — Arab merchants called it the "dinar" in direct derivation. The consistency of the coin's gold content was deliberate policy: Constantinople maintained the solidus at 24 siliquae for over two centuries, a discipline that made it trusted in markets where Byzantine political authority carried no weight.

The mint at Constantinople struck these under the watchful oversight of the comes sacrarum largitionum. Justinian's reconquest campaigns in North Africa and Italy, funded partly through this coinage, drained the treasury sufficiently that later issues occasionally show marginally reduced fineness.