the influence of Roman money, granted peace (218) on comparatively favourable terms. Rome paid a considerable war compensation (50,000,000 denarii), but retained Mesopotamia. Armenia remained with Tiridates, but the latter took it as in dependency on the Romans. In Osrhoene also the old princely house was reinstated. [Sidenote: King Ardashir.] This was the last treaty of peace which the Arsacid dynasty concluded with Rome. Almost immediately afterwards, and perhaps partly in consequence of this bargain, which certainly, as things stood, might be looked upon by the Orientals as an abandonment by their own government of the victories achieved, the insurrection began, which converted the state of the Parthians into a state of the Persians. Its leader, king Ardashir or Artaxares (A.D. 224-241) strove for several years with the adherents of the old dynasty before he attained full success;[78] after three great battles, in the last of which king Artabanus fell, he was master in the Parthian empire proper, and could march into the Mesopotamian desert to subdue the Arabs of Hatra and thence to advance against the Roman Mesopotamia. But the brave and independent Arabs defended themselves now against the Persians as formerly against the Roman invasion, in their huge walls with good success; and Artaxares found himself led to operate in the first instance against Media and Armenia, where the Arsacids still maintained themselves, and the sons of Artabanus had found a refuge. It was not till about the year 230 that he turned against the Romans, and not merely declared war against them, but demanded back all the provinces which had formerly belonged to the kingdom of his predecessors, Darius and Xerxes--in other words, the cession of all Asia. To emphasise his threatening words, he led a mighty army over the Euphrates; Mesopotamia was occupied and Nisibis besieged; the enemy’s cavalry appeared in Cappadocia and in Syria. [Sidenote: Severus Alexander.]