Arsaces I of Parthia

Arsaces I was the first king of Parthia, as well as the founder and eponym of the Arsacid dynasty of Parthia, ruling from 247 BCE to 211 BCE. 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 (now shared between Turkmenistan and Iran) 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-grand nephew, Mithridates I, who assumed the ancient Near Eastern royal title of King of Kings. Arsaces was succeeded by his son Arsaces II, also called Artabanus I

Literary sources are very scarce on Arsaces, and exclusively come from contradictory Greek accounts written centuries after his death. As a result, his reign is sparsely known.

Source
https://en.wikipedia.org/wiki/Arsaces_I_of_Parthia