Islam, which emerged in the Arabian peninsula in the early 7th century soon managed to cover the biggest part of the world. Azeri population were converted to Islam with by the early representatives of this religion in the 18th year of Muslim era (639). Marzban of Azerbaijan Isfandiyar bin Farrukhzad was defeated by Arabs and concluded the contract in the same year. Arabs occupied Ardebil, Tebriz, Nakhichevan, Beylagan, Barda, Shirvan, Mugan and Arran thus reaching Derbend across the Caspian seashore. The fortifiers of the town resisted Arabs which attached the city the name "Bab al-Abvab". Historian Belaruzi reported that the majority of the Azerbaijan's population accepted Islam in period of ruling of khalif Ali bin Abu Talyb (656-661). This process lasted a bit longer on the North. Arabs imposed taxes on the population of the occupied lands, continued invasions after striking the peaceful agreement and later returned back. They resumed invasions as the local population refused paying taxes.

Some regions were converted into Islam peacefully while others were made accept the religion forcefully. The idolaters were suggested to accept Islam, those who did, had to pay zekat and kharadj and did not take part in battles together with Muslims; those participating were granted some of captured materials; while those not accepting the religion had to pay djizya and were under the protection of Muslims; and those refusing to accept the religion or pay djizya had to fight against Mislims. Borderline settlements-ribads were inhabited only by Muslims. Muslims were moved to these regions from different provinces of the Caliphate to consolidate these regions while those who had not accepted Islam were driven to remote places called rebed.

Peace agreements struck by such Arabian commanders as Huzeyfe bin al-Yeman, Utbe bin Ferged, Velid bin Ugbe, Selman bin ar-Rabia al-Bahili, Bukeyr bin Abdullah, Surage bin Emr, Mesleme stipulated for inviolability of the life, property and religion of the population.

The form of converting Azerbaijan into Islam is difficult to speak on as this matter has not yet been studied properly. However, it's possible to single out some of the stages of this process.

The first stage which lasted from the mid 7th century till the early 8th century was the period of progress of Islam. This stage ends with the overthrow of Albania and the loss of independence by Albanian church in 705. According to academician Z.Bunyadov Islam dominated Azerbaijan at the end of this stage and state officials accepted this religion unconditionally to preserve their privileges. The new religion spread among merchants and artisans as Arabs granted privileges to this strata. Mosques were not built at that time and ancient temples and churches, which became useless as a result of the spread of Islam, the predominance of tribal consciousness over religious consciousness was preserved.

The second stage covers the period from the 8th century to the reign of Buveyhiles in West Iran and Iraq. The Independent states of Shirvanshah Mazyadis and Sadjis were established in Azerbaijan. Idolatry and Zoroastrism lost their actuality, Judaism managed to survive, the independence of Albania was restored, yet due to its weak influence the praying ceremonies were held in Armenian language and their followers were armenified. The consciousness of belonging to Islam strengthened at that period yet the ideas connected with the ethnic roots had not yet been completely lost. This can be observed in the shuubism movement which was launched within the first years of the ruling of Abbasies. Babek's (816-838) rebellion is the brightest example of that process. The theosophy of Islam developed in the borderline regions. Radical shiism intensified in the mountain regions.

The third stage embraces the period of the Buveyhivs' ruling (935-1055). Neutral shiism was formed in Azerbaijan and reached Derbend at that time. Shiism and Sunnism were the principle religious trends. Sufism was also quite widely spread among certain groups of people. One of the most beautiful monuments of Sufism was the cloister for dervishes on the Pirsaat river of Shirvan.

The fourth stage coincides with the times of Seldjugs (the mid 11th-mid 13th centuries). Sunnism strengthened while the position of Shiism weakened. Shafiism became the leading trend at that time and the sects of Sufism were widely spread. The Atabeys and Shirvanshahs managed to protect Islam from the pressure of Christianity.

The fifth stage covers the period of Mongolian invasions (the mid 13th-mid 15th century) Sufism was widely-spread at that time and hurufism strengthened its position. It was founded by Fazlullah Naimi (died in 1394). Abulhasan Aliyyul and poet Nasimi (died in 1417) were the most influential representatives of this trend. The second old man of the secret sect of Sufism Seyyid Yahya Shirvani Bakuvi KHelveti (died in 1464) was famous at that time. One of the borther of Aggoyunlu ruler Uzun Gasan was the follower of the sheikh of the sect Dede Omar Rovsheni (died in 1487). Ibrahim bin Mohamed Gulsheni (died in 1534) founded the trend of Gulshaniyye as one the branches of the said sect in the second half of the 15th century. Later a number of trends in Sufism as negshbendiyye spread to Azerbaijan and the North Caucasus through Azerbaijan.

The sixth stage is connected with the ruling of Sefevis (1501-1786) and Osmanlys since the 16th century (1281-1924). Sefevis propagandized Shiism and put on turbans with twelve red strips in the glorification of the 12 imams of Shiism. Therefore they were called Gyzylbashs. Osmanlys which defeated Sefevis in the battle at Chaldyran spread Sunnism in Azerbaijan.

The period of Azerbaijan's annexation to the Russian Empire can also be regarded as a new stage in the religious life of the country. This period is Spiritual leaders of Azerbaijannotable for the attempts of the government to subdue Muslim priests through the policy of establishing the religious structure of Islam similar to that of the Christian church. The letter that was sent to the Senate by the Russian Tsar on November 29, 1832 proposed to work out the statue on the department for work with Transcaucasia Muslims. However, none of the prepared drafts was approved. The official of the Minister of Foreign Affairs M.Khanykov by the instruction of knyaz Volontsov worked out the draft statue on formation of Mohamed's clergymen in 1849. Though the draft was fully approved, it was not implemented due to the commencement of the Crimea war. A new commission was established to continue this work in 1864 and local representatives of Shiism and Sunnism were also involved into the it. Prepared regulations controlled the positions of Muslim clergymen, rights and privileges and relations with the secular government. Only sheyhulislam and Mufti got wage from the government till 1867 while other Muslim clergymen started to get it beginning from this year. The regulation on the department for Islamic Sunnite and Shiite clergymen of Transcaucasia, introduced by the State council was ratified by the Tsar of Russia on April 5, 1872.

The department was mainly based on the structure of the Orthodox church. Two Muslim administrative bodies-the Sunnite Religious department leaded by the Mufti and the Shiite Religious Department chaired by Sheyihulislam-were set up in the Caucasus. Each of these two departments locating in Tiflis was composed of the chair, three members of presidium, two assistants along with the secretary, dragoman, clerk and registrar. Both two departments included four Assemblies in Tbilisi, Yerevan, Yelizavetpol (Ganja) and Baku provinces. The Sunni department included 16 confessors and Shiite-20 of them. The departments acted under the Ministry of Foreign Affairs and reported directly to the governor. Provincial clergymen were controlled by the local government bodies.

The religious affairs of the Caucasus Muslims had been regulated by these two departments until the establishment of the Democratic Republic of Azerbaijan (1918-1920). Sheyhulislam Mohamed Pishnamazzade sent into resignation on December 11, 1918. Akhund Agha Alizade was appointed Sheyhulislam by the decree of Musa Rafibeyov, the Minister of Social Insurance and Religious Conviction of the Democratic Republic of Azerbaijan. This period was notable for strengthening of tendencies which aimed at rationing and modernizing of Islam.

Following the establishment of the Soviet government tin Azerbaijan in 1920 the Ministry of Religious Conviction and sheikhulislamism were dismissed on May 15, Muslim clergymen were persecuted, most of the Mosques were closed down. The creation of Religious structure of Trancscaucasia Muslims was considered advisable for the use of religion in struggle against German fascism in 1943.

The first session of the Transcaucasia Muslims was held in Baku on May 25-28 and the Religious Department for Transcaucasia Muslims was established in this city. Akhund Agha Alizade was appointed sheykhulislam. He is the first elected sheykhulislam as those preceding him were appointed by the government. Moreover, the dualism was abolished in the religious organizations of the Caucasus Muslims in 1944. The Religious Department of Transcaucasia Muslims became a common center that was controlled by Sheykhulislam, Mifli was considered the first deputy chair of the Department and regulated the problems of Sunnites.

This department acts as the Caucasus Muslims Department and is the center of all other religious communities of Islam.