In her doctoral dissertation, Sarah Hillebrand suggests he came from Gallia Narbonensis;[4] however, John D. Grainger asserts Postumus was a native of Italy.
Another is that Postumus may have refused to participate in service to Domitian, as had a number of other senators such as Quintus Corellius Rufus.
One more office can be deduced for Postumus: legatus legionis or commander of one of the legions stationed in Syria, which would explain the presence of his inscription in that province.
Yet the composition of that year is unusual, both in having twelve names -- far more than was usual for that decade -- and having Trajan as ordinary consul for six months.
[9] Where the consuls of the first half of 98 all are notable senators enjoying their second consulships, Grainger notes that the six populating the last half, such as Postumus, are "generally Italian nonentities, the professional senators who gained their posts by virtue of their wealth and lived on long enough to become governors of Asia or Africa when their turn came.