Аршакиды
The city of Semnan has historically been one of the fourteen civil establishments of the ancient, Avesta-era province of "Vern." Semnan remained an important city throughout the era of the Persian Achaemenid Empire. After the invasion of Alexander the Great, which resulted in the fall of the Achaemenid Empire, and the establishment of the Seleucid Empire, the region which hosts the city of Semnan became known as Komesh. The beginning of the prosperous era of the city arrived with the rise of the Arsacid Dynasty of Parthia. The Parthians are an Iranian people. The Arsacid Dynasty of Parthia was very interested in the importing of Hellenism, or Greek culture. This resulted in the pioneering of sculpting and other forms of Western art in the city of Semnan. One of the capital cities of the Parthian Empire was Hecatompylos, and its ruins and numerous historical sites remain between the modern day city of Semnan and Damghan. With the fall of the Parthian Empire, and the rise of the Persian Sassanid Empire, Zoroastrianism was chosen as the state religion, and the city of Semnan was once again brought under the reign of Persian customs and traditions.