Philip the Arab
As the only known evidence for his existence is the two coins, the exact time and extent of Silbannacus's rule is not known. Based on the design of the coin and its silver content, Silbannacus was most likely concurrent with the reigns of Philip the Arab (244–249), Decius (249–251), Trebonianus Gallus (251–253), Aemilian (253), or Valerian (253–260). The two most prevalent ideas are the older hypothesis, that Silbannacus was a usurper in Gaul during the reign of Philip the Arab, at some point between 248 and 250, and the newer hypothesis, based on the design of the second coin, that Silbannacus was a briefly reigning legitimate emperor, holding Rome between the death of Aemilian and the arrival of Valerian.