During the late 6th century BC, the first geographical entity that was called Armenia by neighboring populations was established under the Orontid Dynasty within the Achaemenid Empire, as part of the latters' territories. The kingdom became fully sovereign from the sphere of influence of the Seleucid Empire in 190 BC under King Artaxias I and begun the rule of the Artaxiad dynasty. Armenia reached its height between 95 and 66 BC under Tigranes the Great, becoming the most powerful kingdom of its time east of the Roman Republic.