The roots of that iconography lie in a hagiographic narrative set during the reign of the Emperor Diocletian, which tell of a man named Reprebus, Rebrebus or Reprobus (the "reprobate" or "scoundrel") being captured by Roman forces fighting against tribes dwelling to the west of Egypt in Cyrenaica and forced to join the Roman numerus Marmaritarum or "Unit of the Marmaritae", which suggests an otherwise-unidentified "Marmaritae" (perhaps the same as the Marmaricae Berber tribe of Cyrenaica). He was reported to be of enormous size, with the head of a dog instead of a man, both apparently being typical of the Marmaritae.