40 Nummi - Justinian the Great

Justinian's follis reform of 538 AD increased the weight of the 40-nummi piece significantly from its earlier, lighter incarnation — a deliberate response to complaints that the post-reform 537 coins were still underweight relative to their face value. The regnal year system introduced on these bronzes, marking each coin with the year of Justinian's reign, was an administrative innovation with no real precedent in earlier Roman or Byzantine coinage.

Constantinople, Nicomedia, Cyzicus, Antioch, and Thessalonica all struck this denomination concurrently, and mint attribution remains one of the more active areas of specialist debate for the series.