165 Great plague, originating in Parthia, spreads over the whole world.
166 Peace with Rome. Mesopotamia becomes a Roman province. Parthia begins steadily to decline.
191 Death of Vologases III. Vologases IV succeeds.
194 Vologases permits the Medes to assist Orrhœne in revolt against the Romans.
196 The Parthians ravage Mesopotamia.
199 Severus surprises the Parthians and takes Seleucia, Coche, and Ctesiphon.
201 Siege of Atra by Severus, who is compelled to raise it.
209 Vologases succeeded by his son, Vologases V.
213 His brother, Artabanus (IV), appears as a claimant of the throne. Civil war.
215 Caracalla demands the surrender of Tiridates, brother of Vologases IV, who has taken refuge with Vologases V. The latter refuses to give him up. Caracalla declares war, and the exile is delivered up. Artabanus gains the upper hand and holds Ctesiphon. Caracalla declares war on Artabanus on the latter’s refusal to give his daughter to the Roman emperor.