The mountain region of Ghor province is historically known as Mandesh.
Before the 12th century the inhabitants of the area was Buddhists, Zoroastrians and a small number of Jews. The Lithuanian archeologists discovered the ruins of oldest settlements in Ghor in 2007 and 2008 in the surroundings of Chaghacharan which relates to 5000 BC.
During the Ghurids era Islam was flourishing in the region and all of the residents of Ghor were converted into Islam. It was impressive that how Ghurids took the power from Ghur of a small isolated mountainous area located between the Ghaznavid Empire and the Seljukids. The area was so remote that till the 11th century it remained in isolation surrounded by Muslim principalities.
The area was converted into Islam in early 12th century when Mahmud conquered this region and left some instructors whose responsibilities are to teach Ghurids about the principle of Islam. It is believed that till the end of that century there were a few number of Mahayana Buddhism who were also residing in the region.
Just like other scholars and historians, John McLeod also embraces the conversion of Ghauris to Islam under the hand of Mahmud Ghazni after the Islamizing of Ghor province he went toward central Afghanistan where more people were converted to Islam by Mahmud.
Ghor was also known as Ghoristan, a mountainous country situated between Hirat & Ghazni. In the writings of Istakhri & Ibn Hulkat the traditional Muslim historians they described this are as a rough mountainous country which shares its border with other districts like Herat, Farrah, Dawar, Rabat, Kurwan & Gharistan which were all Muslim countries. Ghor was considered as the country of Infidels and there were only few Muslims residing in the region. The inhabitants of Ghor use to speak the language which was different from the language of Khurasan.
Minhauj S-Siraj another traditional Muslim historian writes about the conflict between the Muslim and non-Muslim population in the province. He records that Amir Suri was a great ruler who has the possession of the most of Ghor territories but as the Islam was not yet embraced by high and low degree of inhabitants that’s why there were continuous conflicts among them. The Saffarians took this as an opportunity they came from Nimroz and Yakub Lais overcame Lak-Lak the chief of Takinabad in Rukhaj country.
The Ghorians flee to Sara-Sang for safety and stayed their but even after that the conflicts among the Muslims and infidels remained. Then Mahmud of Ghazni captured Amir Suri along with his son and prisoned them in Ghazni where Amir Suri died.
In the 11th century AD Mahmud of Ghazni fought a battle with prince of Ghor Ibn-I-Suri who was a Hindu by religion and defeated him, after which he was prisoned in the valley of Ahingaran.
Between 1011 and 1020 both Mahmud and Masud I continued there expeditions and spread Islam in the neighboring country of Ghor as well. After this Ghor became the center of Ghaznavid Empire.
Ghor was also the center of Ghurid dynasty in 12th and 13th century, but later on in 1222 after the invasion of Mongals it was destroyed and sacked including the Minaret of Jam.