"[73][74][75] For some time afterwards, the term "Azerbaijanis" was then applied to all Turkic-speaking Muslims in Transcaucasia, from the Meskhetian Turks in southwestern Georgia, to the Terekemes of southern Dagestan, as well as assimilated Tats and Talysh.

[89]: 48  Conversion to Islam was slow as local resistance persisted for centuries and resentment grew as small groups of Arabs began migrating to cities such as Tabriz and Maraghah.

The emerging dominance of the Turkic language was chronicled in epic poems or dastans, the oldest being the Book of Dede Korkut, which relate allegorical tales about the early Turks in the Caucasus and Asia Minor.

Noted for achievements in state-building, architecture, and the sciences, the Safavid state crumbled due to internal decay (mostly royal intrigues), ethnic minority uprisings and external pressures from the Russians, and the eventually opportunistic Afghans, who would mark the end of the dynasty.

The Safavids encouraged and spread Shi'a Islam, as well as the arts and culture, and Shah Abbas the Great created an intellectual atmosphere that according to some scholars was a new "golden age".

[92] After the Safavid state disintegrated, it was followed by the conquest by Nader Shah Afshar, a Shia chieftain from Khorasan who reduced the power of the ghulat Shi'a and empowered a moderate form of Shi'ism,[89]: 300  and, exceptionally noted for his military genius, making Iran reach its greatest extent since the Sassanid Empire.

Despite the Russian conquest, throughout the entire 19th century, preoccupation with Iranian culture, literature, and language remained widespread amongst Shia and Sunni intellectuals in the Russian-held cities of Baku, Ganja and Tiflis (Tbilisi, now Georgia).

The intellectual and newspaper editor Ali bey Huseynzade (1864-1940) led a campaign to ‘Turkify, Islamise, modernise’ the Caucasian Tatars, whereas Mammed Said Ordubadi (1872-1950), another journalist and activist, criticized superstition amongst Muslims.

Although the bulk of the newly formed Azerbaijani army was engaged in putting down an Armenian revolt that had just broken out in Karabakh, Azeris did not surrender their brief independence of 1918–20 quickly or easily.

In the quest to impose national homogeneity on a country where half of the population were ethnic minorities, Reza Shah banned in quick succession the use of the Azerbaijani language in schools, theatrical performances, religious ceremonies, and books.

[133] They claim there is evidence that, due to repeated invasions and migrations, the aboriginal Caucasian population may have gradually been culturally and linguistically assimilated, first by Iranian peoples, such as the Persians,[134] and later by the Oghuz Turks.

[45] The migration of Oghuz Turks from present-day Turkmenistan, which is attested by linguistic similarity, remained high through the Mongol period, as many troops under the Ilkhanids were Turkic.

[139][140][141] According to Encyclopaedia Iranica, Azerbaijanis mainly originate from the earlier Iranian speakers, who still exist to this day in smaller numbers, and a massive migration of Oghuz Turks in the 11th and 12th centuries gradually Turkified Azerbaijan as well as Anatolia.

[142] According to Encyclopædia Britannica, the Azerbaijanis are of mixed descent, originating in the indigenous population of eastern Transcaucasia and possibly the Medians from northern Iran.

[154] Another 2004 study that looked into 910 MtDNAs from 23 populations in the Iranian plateau, the Indus Valley, and Central Asia suggested that populations "west of the Indus basin, including those from Iran, Anatolia [Turkey] and the Caucasus, exhibit a common mtDNA lineage composition, consisting mainly of western Eurasian lineages, with a very limited contribution from South Asia and eastern Eurasia".

[157] A 2007 study which looked into class two Human leukocyte antigen suggested that there were "no close genetic relationship was observed between Azeris of Iran and the people of Turkey or Central Asians".

[159] In a 2019 study examining genome-wide data from selected populations in North Africa and West Eurasia, Azeris were grouped with Balkars, Circassians, Georgians, Lezgins, and Turkish people.

According to Ethnologue, there are over 1 million speakers of the northern Azerbaijani dialect in southern Dagestan, Estonia, Georgia, Kazakhstan, Kyrgyzstan, Russian proper, Turkmenistan, and Uzbekistan.

[163] Azerbaijan began the twentieth century with institutions based upon those of Russia and the Soviet Union, with an official policy of atheism and strict state control over most aspects of society.

[164] Despite these problems, there is a financial rebirth in Azerbaijan as positive economic predictions and an active political opposition appear determined to improve the lives of average Azerbaijanis.

Even though all Iranian censuses of population distinguish exclusively religious minorities, numerous sources have presented different figures regarding Iran's Turkic-speaking communities, without "any justification or concrete references".

Shortly after, this figure was replaced by thirty million, which became "almost a normative account on the demographic situation in Iran, widely circulating not only among academics and political analysts, but also in the official circles of Russia and the West".

[169] Azerbaijani minorities live in the Qorveh[172] and Bijar[173] counties of Kurdistan, in Gilan,[174][175][176][177] as ethnic enclaves in Galugah in Mazandaran, around Lotfabad and Dargaz in Razavi Khorasan,[178] and in the town of Gonbad-e Qabus in Golestan.

Arakelova adds that the number of Tehran's inhabitants who have migrated from northwestern areas of Iran, who are currently Persian-speakers "for the most part", is not more than "several hundred thousands", with the maximum being one million.

[209] Past Iranian leaders, such as the reformer ex-president Mohammad Khatami promised women greater rights, but the Guardian Council of Iran opposes changes that they interpret as contrary to Islamic doctrine.

Composers Uzeyir Hajibeyov, Gara Garayev and Fikret Amirov created a hybrid style that combines Western classical music with mugham.

Some Azerbaijani musicians have received international acclaim, including Rashid Behbudov (who could sing in over eight languages), Muslim Magomayev (a pop star from the Soviet era), Googoosh, and more recently Sami Yusuf.

According to Iranian singer Hossein Alizadeh, "Historically in Iran, music faced strong opposition from the religious establishment, forcing it to go underground.

Iranian athletes of Azerbaijani origin have particularly excelled in weight lifting, gymnastics, shooting, javelin throwing, karate, boxing, and wrestling.

[228] Weight lifters, such as Iran's Hossein Reza Zadeh, world super heavyweight-lifting record holder and two-time Olympic champion in 2000 and 2004, or Hadi Saei, a former Iranian.