Phriapatius sometimes called Phriapites, 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....

 from 191 BC to 176 BC. He was the grandson of Tiridates I of Parthia

Tiridates I of Parthia

Tiridates, or Teridates is a Persian name, given by Arrian in his Parthica to the brother of Arsaces I, the founder of the Parthian kingdom, whom he is said to have succeeded in about 246 BC...

 (246–211 BC), the brother of Arsaces I of Parthia

Arsaces I of Parthia

Arsaces I was the founder of the Arsacid dynasty, and after whom all 30+ monarchs of the Arsacid empire officially named themselves. A celebrated descent from antiquity begins with Arsaces.A 1st century AD tradition casts Arsaces as descending from the 5th-century BC Achaemenid monarch...

 (250–211 BC), the founder of the Parthian Empire.

He ruled in the period following the invasion of Parthia by the Seleucid

Seleucid dynasty

The Seleucid dynasty or the Seleucidae was a Greek Macedonian royal family, founded by Seleucus I Nicator , which ruled the Seleucid Kingdom centered in the Near East and regions of the Asian part of the earlier Achaemenid Persian Empire during the Hellenistic period.-History:Seleucus was an...

 king Antiochus III (223–187 BC).

He was the father of three Parthian kings, Phraates I

Phraates I of Parthia

Phraates I of Parthia, ruler of the Parthian Empire from 176-171 BCE, succeed his father Phriapatius on the throne. Died relatively young, and appointed as his successor not one of his sons, but his brother Mithridates I ....

 (176–171 BC), who was his successor, Mithridates I

Mithridates I of Parthia

Mithridates or Mithradates I was the "Great King" of Parthia from ca. 171 BC - 138 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...

 (171–138 BC), and Artabanus I

Artabanus I of Parthia

Artabanus I of Parthia ruled the Parthian Empire from c. 128 to 124 BC. He succeeded his nephew Phraates II and died, just like his predecessor, in battle against the Tochari - a name commonly identified with the Yuezhi of the Chinese sources, who had fled from Gansu in northwest China, via the Ili...

 (138–124 BC).