It is largely through linguistic similarities that the Iranian people have been linked, as many non-Iranian people have adopted Iranian languages and cultures. However, other common traits have been identified as well and a stream of common historical events have often linked the southern Iranian people, including Hellenistic conquests, the various empires based in Persia, Arab Caliphates and Turkic invasions.

Although most of the Iranian people settled in the Iranian plateau region, many expanded into the periphery, ranging from the Caucasus and Anatolia to the Indus. The Iranian people have often mingled with other populations, with the notable example being the Hazaras, who display a distinct Turko-Mongol background that contrasts with most other Iranian people.^[35] Similarly, the Baloch have mingled with the Dravidian-speaking Brahui (who have been strongly modified by Iranian immigrants themselves), while the Ossetians have invariably mixed with Georgians and other Caucasian people. The Pashtuns vary with some having mingled with fellow Iranian groups such as the Tajiks and Turkic people and those to the east who have mingled with Dardic and Nuristani people. Moreover, the Kurds are an eclectic Iranian people who, although displaying some ethnolinguistic ties to other Iranian people (in particular their Iranian language and some cultural traits), are believed to have mixed with other groups, for example peoples from the Caucasus and Semitic people.^[19][36] Modern Persians themselves are also a heterogeneous and eclectic group of people descended from various ancient Iranian, Semitic, and indigenous people of the Iranian plateau, including the Elamites.^[37] Thus, not unlike the aforementioned example of Germanic people including the English, who are both of Germanic and Celtic origin, Iranians are an ethno-linguistic group and the Iranian people display varying degrees of common ancestry and cultural traits that denote their respective identities.

Culture

Many of the cultural traits of the ancient Iranians were similar to other Proto-Indo-European societies. Like other Indo-Europeans, the early Iranians practiced ritual sacrifice, had a social hierarchy consisting of warriors, clerics and farmers and poetic hymns and sagas to recount their deeds.^[11]

Following the Iranian split from the Indo-Iranians, the Iranians developed an increasingly distinct culture. Various common traits can be discerned among the Iranian people. For example, the social event Norouz is an Iranian festival that is practiced by nearly all of the Iranian people as well as others in the region. Its origins are traced to Zoroastrianism and pre-historic times.

Some Iranian people exhibit distinct traits that are unique unto themselves. The Pashtuns adhere to a code of honor and culture known as Pashtunwali, which has a similar counterpart among the Baloch, called Mayar, that is more hierarchical.^[38]

Religion

The early Iranian people worshipped various deities found throughout other cultures where Indo-European immigrants established themselves.^[39] The earliest major religion of the Iranian people was Zoroastrianism, which spread to nearly all of the Iranian people living in the Iranian plateau. Other religions that had their origins in the Iranian world were Mithraism, Manichaeism, and Mazdakism, among others.

Modern speakers of Iranian languages mainly follow Islam. Some follow Judaism, Christianity, Zoroastrianism, and the Bahá'í Faith, with an unknown number showing no religious affiliation. Overall the numbers of Sunni and Shia among the Iranian people are equally distributed. Most Kurds, Tajiks, Pashtuns, and Baluchis are Sunni Muslims, while the remainder are mainly Shi'a, comprising mostly of Persians in Iran, Zazas in Turkey, Hazaras in Afghanistan, and Pamiri peoples in Tajikistan and China. The Christian community is largely represented by the Russian Orthodox and Georgian Orthodox Ossetians followed by Nestorians. Judaism is followed mainly by Persian Jews, Kurdish Jews and Mountain Jews (of the Caucasus), most of which are now found in Israel. The historical religion of the Persian Empire was Zoroastrianism and it still has a few thousand followers, mostly in Yazd and Kerman. They are known as the Parsis in the Indian subcontinent, or Zoroastrians in Iran.

Cultural assimilation

In matters relating to culture, the various Turkic-speaking minorities of Iran (notably the Azerbaijani people) and Afghanistan (Uzbeks and Turkmen) are often conversant in Iranian languages, in addition to their own Turkic languages and also have Iranian culture to the extent that the term Turko-Iranian can be applied.^[40] The usage applies to various circumstances that involve historic interaction, intermarriage, cultural assimilation, bilingualism and cultural overlap or commonalities.

Notable among this synthesis of Turko-Iranian culture are the Azeris, whose culture, religion and significant periods of history are linked to the Persians.^[41] Certain theories and genetic tests^[42] suggest that the Azeris are descendants of ancient Iranian peoples who lost their Iranian language (see Ancient Azari language) following the Turkic invasions of Azerbaijan in the 11th century CE. In fact, throughout much of the expanse of Central Asia and the Middle East, Iranian and Turkic culture has merged in many cases to form various hybrid populations and cultures, as evident from various ruling dynasties such as the Ghaznavids, Seljuqs and Mughals.

Iranian cultural influences have also been significant in Central Asia, where Turkic invaders are believed to have largely mixed with native Iranian people of which only the Tajik remain, in terms of language usage. The areas of the former Soviet Union adjacent to Iran (such as Azerbaijan and Uzbekistan) have gone through the prism of decades of Russian and Soviet rule that has reshaped the Turko-Iranian cultures there to some degree.