History of Parthia
Parthia began small when Arsakes I of the Parthian Satrapy led a successful
rebellion against Selukid rule in 238 BC. The Parthians created an
empire covering most of the old Persian Empire except along the Mediteranian
coast that Romans tenaciously held. Although many wars were fought between
the Romans and Parthians the Romans never had a successful campaign into
Parthian territory and generally only recovered previously lost territories.
In 224 AD, the Parthian Govenor of the province of Persis (Ardashir) revolted
and established the Sasanid dynasty. The last Parthian king Vologases VI was
defeated in 228 AD. It should be noted that any reference by Romans to Parthia
after 228 AD should actually be to Sasanid.