Arsaces I was the first king of Parthia, ruling from 247 BC to 217 BC, as well as the founder and eponym of the Arsacid dynasty of Parthia. The leader of the Parni, one of the three tribes of the Dahae confederacy, Arsaces founded his dynasty in the mid-3rd century BC when he conquered the satrapy of Parthia from Andragoras, who had rebelled against the Seleucid Empire. He spent the rest of his reign consolidating his rule in the region, and successfully stopped the Seleucid efforts to reconquer Parthia. Due to Arsaces' achievements, he became a popular figure amongst the Arsacid monarchs, who used his name as a royal honorific. By the time of his death, Arsaces had laid the foundations of a strong state, which would eventually transform into an empire under his great-grandnephew, Mithridates I, who assumed the ancient Near Eastern royal title of King of Kings. Arsaces was succeeded by his son Arsaces II.

Antiochus III the Great was a Greek Hellenistic king and the 6th ruler of the Seleucid Empire, reigning from 223 to 187 BC. He ruled over the region of Syria and large parts of the rest of western Asia towards the end of the 3rd century BC. Rising to the throne at the age of eighteen in April/June 223 BC, his early campaigns against the Ptolemaic Kingdom were unsuccessful, but in the following years Antiochus gained several military victories and substantially expanded the empire's territory. His traditional designation, the Great, reflects an epithet he assumed. He also assumed the title Basileus Megas, the traditional title of the Persian kings. A militarily active ruler, Antiochus restored much of the territory of the Seleucid Empire, before suffering a serious setback, towards the end of his reign, in his war against Rome.