Dux Foenicis

[Nathan Ross]

Exact boundaries would have followed the general operational area of the border fortresses which are listed in the ND.

I was referring more to the boundaries between the various Roman provinces, which would have been easier for the Romans to adjudicate! The eastern boundary itself was probably far from exact - the limes on any frontier was more of a zone than a strict line of demarcation. While the Strata Diocletiana gives a rough parallel for the frontier area, Roman control more probably extended, as you suggest, to the limits of the operational areas rather than to a fixed 'line in the sand'!

Interesting about the allied Arab units.

I think Evan was referring to the various desert peoples - the Saracens or Sarakenoi, distinct from the settled Arabs of the Roman provinces - rather than to Roman irregular units. These peoples - Tanukhids, Salih and later Ghassanids - were usually allied to Rome as foederati or symmachoi, although sometimes they rebelled against Roman control.

The Saracens and the Romans appear to have had quite different ideas about territorial definition. While the Romans were keen on frontiers, the Saracens were not, and seem to have roamed at will both inside and outside the frontier zone. Saracen bands and temporary settlements appear well within the Roman provinces at times (there was a large settlement of Tanukhids near Aleppo, apparently) but they don't seem to have respected the actual frontiers to any great extent!

Irfan Shahid's monumental multi-volume work on Byzantium and the Arabs is now available online - I read the volume on the fourth century some time ago, and it has quite a lot of information on the Notitia Dignitatum and the frontier situation. Shahid does make some very speculative claims (that the Magister Militum Victor was actually named Silvanus, and an inscription in Syria mentioning his wife Chasidat actually relates to the daughter of Mavia, for example), but his work is packed with details and well worth plumbing through:

Shahid - Byzantium and Arabs in the Sixth / Fifth / Fourth Century (Dumbarton Oaks)