Mithridates or Mithradates I (Parthian: Mithradat, , Mehrdad), (ca. 195 BC – 138 BC) was king of the Parthian Empire from 165 BC to 132 BC, succeeding his brother Phraates I. His father was King Phriapatius of Parthia, who died ca. 176 BC). Mithridates I made Parthia into a major political power by expanding the empire to the east, south, and west. During his reign the Parthians took Herat (in 167 BC), Babylonia (in 144 BC), Media (in 141 BC) and Persia (in 139 BC). Because of his many conquests and religious tolerance, he has been compared to other Iranian kings such as Cyrus the Great (d. 530 BC), founder of the Achaemenid Empire.