Mauseus,
It's clearly Trajan's
type repeated, so reference should again be to
Mesopotamia. It's possible that
Caracalla undertook a new campaign against the
Parthians c. 206-7, of which there is no mention in the literary sources.
Some extracts from an article by Andrew
Burnett in Bulletin of the Institute of
Classical Studies, University of
London, 2016:
"The clearest
type on the coinage of
Rome occurs in 207 (
Caracalla’s TR P X) and has the
legend PONTIF TR P X
COS II or
VIRTVS AVGG with a standing emperor between two river-gods and a captive (
BMCRE S and C 555, 520) (Figs. 12-13).72 It is a close copy of the coins made ninety years earlier by
Trajan, commemorating
his establishment of the province of
Mesopotamia between the Euphrates and the
Tigris (inscribed
ARMENIA ET
MESOPOTAMIA IN POTESTATEM P(opuli) R(
omani) REDACTAE)."
Note 72 "C. Clay points out that the
type is often mis-described as one river-god and two
captives. On clear coins from
fine dies, however, one can see that there are two river-gods and that the captive is even wearing an ‘
Armenian tiara’, as on the coins of
Trajan. On the
denarii the
head of the standing figure is unbearded, indicating
Caracalla (rather than
Severus)."
"It is hard to form a definite view of the strength of this evidence for an otherwise unknown journey or campaign by
Caracalla to the east. One could be sceptical, and assume that the coins from
Rome were making a reference back to the capture of Ctesiphon in 198, but why should the
mint recall that
victory nine years later, and why for
Caracalla only, and not for Septimius too?"