The Treaty of Apamea of 188 BC, was peace treaty between the Roman Republic and Antiochus III (the Great), ruler of the Seleucid Empire. It took place after the Romans' victories in the battle of Thermopylae (in 191 BC), in the Battle of Magnesia (in 190), and after Roman and Rhodian naval victories over the Seleucid navy. The treaty was formalized at Apamea in Phrygia. It allowed the Romans to expand their political hegemony to the East Mediterranean Sea. But at this time Roman power was still indirect. Rome depended on its capacity to ally itself to second rank powers.