King Mithridates III of Parthia ruled the Parthian Empire

Parthia

Parthia is a region of north-eastern Iran, best known for having been the political and cultural base of the Arsacid dynasty, rulers of the Parthian Empire....

 c. 57–54 BC. With the assistance of his brother Orodes

Orodes II of Parthia

Orodes II of Parthia ruled the Parthian Empire from 57 to 38 BC. Orodes was a son of Phraates III, whom he murdered in 57 BC, assisted by his brother Mithridates...

 he murdered his father Phraates III

Phraates III of Parthia

King Phraates III of Parthia succeeded his father Sanatruces and ruled the Parthian Empire from 70 to 57 BC. He was called "the God" because of his coins, that were ideal for sailors because they were polished with gold dust, so that people from other countries considered their value higher than...

. He was made king of Media

Medes

The MedesThe Medes...

 and waged war against his brother, but was soon deposed on account of his cruelty. He took refuge with Aulus Gabinius

Aulus Gabinius

Aulus Gabinius, Roman statesman and general, and supporter of Gnaeus Pompeius Magnus, was a prominent figure in the later days of the Roman Republic....

, the Roman

Roman Republic

The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...

 proconsul

Proconsul

A proconsul was a governor of a province in the Roman Republic appointed for one year by the senate. In modern usage, the title has been used for a person from one country ruling another country or bluntly interfering in another country's internal affairs.-Ancient Rome:In the Roman Republic, a...

 of Syria

Syria

Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....

. He advanced into Mesopotamia

Mesopotamia

Mesopotamia is a toponym for the area of the Tigris–Euphrates river system, largely corresponding to modern-day Iraq, northeastern Syria, southeastern Turkey and southwestern Iran.Widely considered to be the cradle of civilization, Bronze Age Mesopotamia included Sumer and the...

, but was beaten at Seleucia on the Tigris

Seleucia on the Tigris

Seleucia , also known as Seleucia on the Tigris, was one of the great cities of the world during Hellenistic and Roman times. It stood in Mesopotamia, on the west bank of the Tigris River, opposite the smaller town of Ctesiphon, in present day Babil Governorate, Iraq.-Seleucid empire:Seleucia,...

 by Orodes' general Surena

Surena

Surena or Suren may refer to either a noble family of Parthia also known as the House of Suren, or to a renowned 1st century BC General Surena who was a member of that family....

, fled into Babylon

Babylon

Babylon was an Akkadian city-state of ancient Mesopotamia, the remains of which are found in present-day Al Hillah, Babil Province, Iraq, about 85 kilometers south of Baghdad...

, and after a long siege was taken prisoner and killed in 54 BC by Orodes.