According to archeological excavations done all over the province especially in:
- Alikosh, Sabz, Khaziné, Choghā Sefid hills in Dehlorān County, Kezābād and Cheshme-Māhi in Holeylān district which back to prehistoric era
- War-kabud, Kalnesār, Jub-Gowhar, Bardbāl Cemeteries that belong to historic era, and
- Ruins of Seymaré historic city which return to the early lslamic era. It has been understood that human inhabitation in the historic-cultural area of the province, has last sequentially in the different eras.
ilam province is one of the Elamite Ancient civilization's beneficiaries. The brilliant civilization that established in 3rd millennium BC and ruled until 645 BC. Some Ones believe that "Elam" or what Akkadians said "Elamtu", meaning “the high; or mountainous land" or “the land of Sunrise".
After Elamites, Assyrians, Medians, Achaemenids, Seleucids and Parthians ruled on the region. Information and evidences in these eras are not very clear. But in Sassanid era (224-651 BC), due to being nearby the empire's capital Ctesiphon and neighboring Mesopotamia and Khuzestan, the region gained more importance and information are clearer and remains and monuments are further rather than the past eras.
In the Sassanid era, today ilam province was consisted of two provinces: Māspatān (Māsbazān in early lslamic era) in the north with sirvān historic city as its provincial capital and Mehrgān Kadak (Mehrajanqazaq in early lslamic era) in the South with seymaré historic city as its provincial capital. in early lslamic era, these two provinces was part of the greater province called Jebāl (the mountains). The name that Arabs put on the central and western mountainous part of Iran. It was in this time that Al-Mahdi Billah, the fourth Abbasid Caliph that was one of the most well-known ones, died in Māsbazān, Raz Village, On March 934 and buried there. His mausoleum Was situated in today ilam's Kudak Park. it destroyed in 1973 and nothing left behind.
Seymaré historic city was alive until 334 AH (circa 945 BC), before destroying probably by an earthquake.
After this time, the province today borders was part of local ruling family territories called Atabakān-e Lur-e Kuchak; (the minor Lur Atābaks) that ruled on today ilam and Lurestan provinces (12th-16th centuries). In 1597 the Atābaks replaced with another family by Shah Abbas the Great : the Vālis (chieftains) Family. The first ruling Center of the Vālis was in Khorramābād Which is provincial capital of Lurestan. Circa 1801 Hasan Khān emigrated to "Dāwālā" (a Village in which future ilam city built). After this time, this region Was ruling center of Vālis. Hoseyn-Qoly Khān ruled on llam province from 1857 to 1900. He was Hasn Khān's grandson and called the city Hoseynābād. He attempt for developing the city, but his son Gholām-Rezā Khān (1900-1928) was more successful. He was the last Vāli and the most important monument he built is the Vāil Citadel.
After rise of Reza Shah and forming a powerful central government, the last Vāli has been forced to abandon his local power. He did that Without any conflict With central government and left Iran to Iraq forever and died there. in 1935 the city name changed into ilam formally by the Government which suggested before by Academy of Persian Language and Literature in 1930. In the new administrative divisions act in 1937 the region became a county of the Fifth Province (Kermanshahan). in 1964 i|am County was preferred as Farmāndari-ye kol (a rank between county and province) and at last in 1974, became an independent province.