Mailed soldiers on the Arch of Galerius

[jho]

I do not think that it will be possible to identify these people with any reasonable degree of certainty, in particular as the soldiers in the battle scenes of the arch look completely different (with the soldiers most similar to the traditional image of a roman soldier actually fighting AGAINST Galerius).

However, we should keep in mind that there are actually quite similar depictions of soldiers in Rome broadly from this period: the two soldiers on the fragment in the Vatican museums (undated but believed to come from the arch of Diocletian) and the "Egyptian" soldiers on paintings in the catacombs (Graham Sumner's latest book has the references). This may indicate that they were a common sight in Rome and therefore regulars of guard status but cavalry (based on the catacomb paintings). However, all of this is very speculative.