Arsaces I founded the Arsacid dynasty after seizing control of Parthia around 247 BCE.
Arsaces, also written Arsak or Arshak, was the leader of the Parni, a nomadic group from Central Asia. The Parni conquered the northeastern Iranian region of Parthia, which had been governed by the Seleucid Empire after Alexander’s conquests. This takeover traditionally marks the beginning of the Parthian or Arsacid Empire.
Arsaces I established the dynasty, but later kings greatly enlarged its power. Mithridates I transformed the kingdom into a major empire by conquering Media and Babylonia, while Mithridates II strengthened its position against Rome and Central Asian rivals. Later Arsacid monarchs frequently used the name Arsaces as a dynastic title, so individual rulers can be difficult to distinguish.
The Arsacid Empire eventually gave way to the Sasanian dynasty in 224 CE, when Ardashir I defeated the last Arsacid king, Artabanus IV.