 His western neighbours, the Romans, had since their peace treaty with Iran in 387 agreed that both empires were obligated to cooperate in the defense of the Caucasus against nomadic attacks.The Romans helped in the defense of the Caucasus by paying the Iranians roughly 500 lbs (226 kg) of gold at irregular intervals.While the Romans saw this payment as political subsidies, the Iranians saw it as tribute, which proved that Rome was the deputy of Iran.