The exact origins of the current Kermanshah region are difficult to determine. It would have been a part of the vast area called Media.

The province of Kermanshah is considered part of Iranian Kurdistan. It connects Mesopotamia to the Iranian plateau. Excavations near the Bisotoun inscriptions in the area have uncovered a 35,000-year-old site and evidence of Neanderthals' past existence. Other archaeological remains located in the Kangavar Valley and dating back to 5000 BC. AD can today be admired and are comparable in their importance to the archaeological sites of Lorestan and Nahavan. A Neolithic site on one of the slopes of Ganj Dareh Hill dating back to 8450 BCE is considered one of the first known agricultural areas of the Zagros Plain.

The exact origins of the current Kermanshah region are difficult to determine. It would have been a part of the vast area called Media. The fact is that "Kermanshah" was a name known at the time of Bahram IV, the brother or son of Shapur III. Bahram adopted this name before his accession when he was governor of Kerman, and he appears on all Sassanid seals of that time. According to Yaqut al-Homavi (1179-1229), the Arabic name of Kermanshah was Qermisin, while Mostowfi Qazvini (1281-1349) considers the name Qarmasin (and its variants Qermasin and Qarmisin) to be the archaic form of Kermanshah. However, medieval geographers such as Al Muqaddasi (945-991) preferred the term "Kermanshahân".

During the Muslim conquest, Kermanshah surrendered to the Arab forces under Jarir ibn Abdullah Al Bajali. At that time, it was part of the vast province of Jebâl, and was known as one of its four main regions. Following the tax reforms of Caliph Muawiya (602-680), the province became one of two revenue-generating districts to support Kufa's troops. The Achaemenid and Sassanid remains and inscriptions located near Kermanshah in Bisotun and Baq-e Bostan fascinated the first Muslim writers, and were an opportunity for them to create impressive representations (pre-Islamic so) including Khosrow II, Shirin and Farhad, and Shabdiz horse. It should be noted that during the reign of Ziyarid Mardavij (927-935), the Deylamites destroyed the region and enslaved all its inhabitants; this same region Ibn Hawqal described in the tenth century as a prosperous and pleasant place, rich in vegetation, fruits, pastures, herds and water. This description is confirmed by his contemporary Al-Muqaddasi, who adds that the region was also known for the beautiful mosque of its market place.

The politics of the Bouyid period made possible the rise of a few small Kurdish dynasties in the regions around Kermanshah and Dinevar. Under the Seljuks, Kermanshah was still militarily and economically important because of its location at the intersection of the main road linking Baghdad to Khorasan. For the same reason, the region has become a contentious issue in the regional conflicts that punctuated the history of Iran from the twelfth century. In 1197, the Khwarezmian emir Miânjoq looted Kermânshâh. He was on the way to the Hulagu Khan troops (1217-1265) who were traveling from Hamedan to Baghdad. In December 1257, his army destroyed the city and massacred its inhabitants.

From the Mongol era, Kermanshah gained prominence as a strategic border between the Safavid and Ottoman empires. He thus played a particularly crucial role in defending the political activities of the Safavids in Iraq and in countering the Ottoman threats to Azerbaijan. Control of this border area has changed hands between the Safavids and the Ottomans several times, and the power struggle has affected the relations of the two empires with the Kurdish tribes of the region, which has jeopardized the balance of power. powers. Under Shah Tahmasp I (1514-1576), the second Safavid king, the Kurdish tribes of Iran have positioned themselves at the vanguard of the Ottoman-Safavid conflict. During the reign of the first Safavids, the Kalhor were the most powerful Kurdish tribe in Kermanshah province, but from the middle of the 17th century, the Zangeneh family consolidated its position, which had been serving the Safavids since the 16th century. In 1653, Sheikh Ali Khan Zangeneh was named khan of Kalhor, Sonqor and Kermanshah, the homeland of the Zangeneh family. Shah Soleyman I (1647-1694) promoted Sheikh Ali Khan Zangeneh to the Grand Vizierate, a position he held from 1669 to 1689. For the rest of the Safavid period, the Kermanshah region remained under the control of this great family.

Taking advantage of the chaos following the Afghan invasion and the overthrow of the Safavids, the Ottomans resumed their efforts to develop their presence in northwestern Iran. In October 1723, Hasan Pasha, the Ottoman governor of Baghdad, besieged Kermanshah by advancing towards Hamedan. Abd-al-Baqi Khân Zangeneh, governor of Kermânshâh, confessed to being defeated and the Ottomans occupied the city. Hasan Pachah died at Kermanshah in February 1724 and was replaced by his son, Ahmad Paca, who later imposed himself at Hamedan. In the autumn of 1724, the Ottomans seized Kermanshah province, Ardalan, Hamedan, and Lorestan. Ashraf Gilzay, the Afghan leader and pretender to the Iranian throne, crushed the Ottomans near Hamedan in 1726, but to be recognized as Shah, he accepted in 1727 a treaty yielding vast expanses of its provinces to the Ottomans. According to the Turkish registers, many villages in Kermanshah province at that time were depopulated.

Nâder-qoli Beg Afshâr (future Nâder Shâh), after having put the very young Safavid king Tahmasp II on the throne and defeated the Afghans at the battle of Mehmândoust, took control of Kermânshâh and other territories ceded by Ashraf Gilzay. The Ottoman governor of Baghdad, Ahmad Pacha, counterattacked as soon as Nader returned to Khorasan, and occupied Kermanshah. The area was weakly defended by Tahmasp, who lost the battle at Korejan in September 1731. Tahmasp later accepted a treaty ceding territory north of the Araxes to the Ottomans in exchange for their evacuation from the recently occupied territories (the Ottomans withdrew from Hamedan but remained in Kermanshah). Nâder used this event as an excuse to dismiss Tahmâsp and act as regent for the benefit of the future king Abbas III. To attack Ahmad Pacha in Baghdad, Nader gathered an army at Hamedan and besieged Kermanshah at the end of 1732 - a region that was later considered part of Iranian territory. To ensure total control of the region and support future campaigns in Ottoman Iraq, Nadir Shah ordered the construction of a fortress west of Kermanshah, well stocked with weapons and ammunition. The fortress became a crucial place for the control of western Iran and played an important role in the power struggles that led to the assassination of Nader Shah in 1747.