During history, few eras have been as ambiguous and dark as Parthians. In this way, historians undervalue the era between downfall of Achaemenian Monarchy till the formation of Sasanian Monarchy, i.e. five and half century ago (323 BC-226 AD),and have studied this era from Greek-centrism view or like Alexander ’s monarchy. Parthian religion is the fruit of proper political thought behind ruling duties. Mithraism ideology had king’s support and promised salvation and a new after-death world to the soldiers. After Parthians’ conquers and increase of border conflicts in west and northwest of Iran, residues of Zahak can be considered the focus of power center in first Christian century. Since Parthian temples in Iran have not been discovered and foreign neighbors have frequently done it , this study aims to introduce Zahak Temple in northwest of Iran with proper historical, geographic, and cultural backgrounds as a gate of Mithraism entrance to Europe and start point of Iranian thought’ s invasion to west. It uses analytic and adoptive approach utilizing library and field methods.