Mithridates II of Parthia

Mithridates II (also spelled Mithradates II or Mihrdad II; Parthian: 𐭌𐭄𐭓𐭃𐭕 Mihrdāt) was king of the Parthian Empire from 124 to 91 BCE. Considered one of the greatest of his dynasty to ever rule, he was known as Mithridates the Great in antiquity.

Mithridates II was crowned king after the abrupt death of his predecessor Artabanus I. Inheriting a declining empire that was reeling from military pressure in both the east and west, Mithridates II quickly stabilized the situation in Mesopotamia by gaining the allegiance of Characene, and subduing the Arabs, who had continuously raided Babylonia. Mithridates II was the first Parthian king to vassalize Armenia. To the east, he defeated and conquered the nomadic tribes in Bactria who had killed both of his predecessors. Sakastan was also reconquered, which was given as a fiefdom to the House of Suren. In 95 BCE, he invaded Armenia and made it a client state, which would last until 91 BCE. Under Mithridates II, the Parthian Empire at its zenith extended from Syria and Armenia to Central Asia and India. It was under Mithridates II that the Parthian Empire for the first time established diplomatic relations with Han China.

A champion of Achaemenid traditions, Mithridates II was determined to emphasize the association of the ruling Arsacid dynasty with the Iranian Achaemenid Empire. He was the first Parthian monarch to regularly use the title King of Kings, and portray himself with an Iranian tiara on the obverse of his coins, contrary to the Hellenistic diadem used by his earlier predecessors. He also replaced the omphalos on the reverse of his coins with a highbacked throne of Achaemenid origin.

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