Which Persian empire was founded by Arsaces I in 247 BC?

The Persian empire founded by Arsaces I in 247 BC was the Parthian Empire, also called the Arsacid Empire. Its ruling dynasty took its name from Arsaces and his successors.

Arsaces I was leader of the Parni, a nomadic group connected with the Dahae confederacy. In the mid-third century BC, the Parni seized territory in northeastern Iran and established control over Parthia, a former province of the Seleucid Empire. The date 247 BC is traditionally used to mark the beginning of the Arsacid dynasty and the Parthian state, although the initial conquest and consolidation unfolded over several years.

The Parthians eventually became one of Rome’s most powerful eastern rivals. Their empire stretched across much of Iran and Mesopotamia, and their armies became famous for mounted archers and heavily armored cataphracts. They defeated Roman forces at the Battle of Carrhae in 53 BC, capturing the Roman commander Marcus Licinius Crassus. The Seleucid Empire was the older Hellenistic power that ruled the region before the Parthians, while the later Sassanid Empire overthrew the Arsacids in AD 224. The Achaemenid Empire belonged to an earlier Persian dynasty.