Parthia is a region of north-eastern Iran, best known for having been the political and cultural base of the Arsacid dynasts, after which the Arsacid Empire is then also known as the 'Parthian Empire'.

Parthia roughly corresponds to the western half of Greater Khorasan. During Arsacid times, Parthia was united with Hyrcania (which today lies partly in Iran and partly in Turkmenistan) as one administrative unit, and that region is therefore often (subject to context) considered a part of Parthia proper.

The name "Parthia" is a continuation from Latin Parthia, from Parthava, which was the Parthian language self-designator signifying "of the Parthians".

Parthian Empire -  Wikipedia, the free encyclopedia