Mithridates I of Parthia

Mithridates I, also known as Mithridates I the Great, was king of the Parthian Empire from 171 BC to 132 BC. During his reign, Parthia was transformed from a small kingdom into a major political power in the Ancient East as a result of his conquests. He first conquered Aria, Margiana and western Bactria from the Greco-Bactrians sometime in 163–155 BC, and then waged war with the Seleucid Empire, conquering Media and Atropatene in 148/7 BC. In 141 BC, he conquered Babylonia and held an official investiture ceremony in Seleucia. The kingdoms of Elymais and Characene shortly afterwards became Parthian vassals. In c. 140 BC, while Mithridates was fighting the nomadic Saka in the east, the Seleucid king Demetrius II Nicator attempted to regain the lost territories; initially successful, he was defeated and captured in 138 BC, and shortly afterwards sent to one of Mithridates I's palaces in Hyrcania. Mithridates I then punished Elymais for aiding Demetrius, and made Persis a Parthian vassal.