Turkification is a term used to describe a process of cultural change in which something or someone who is not a Turk becomes one, voluntarily or by force. It can be used in contexts in connection with Anatolian, Balkan, Caucasian and Middle Eastern peoples from different ethnic origins, as for example: Albanians, Arabs, Armenian Muslims, Assyrians, Greek Muslims, Jews, Roma, various Slavic peoples (such as Bosniaks and Pomaks), Iranian peoples (mainly Azaris and Kurds and Zazas), as well as Lazs and even Turkic ethnicities (such as Tatars) from all regions of Ottoman Empire. Another meaning of the term includes the earlier assimilative processes of the indigenous peoples in Anatolia. They occurred trough religious conversion, cultural and language assimilation during the time of Seljuk Empire. The use of the term does not assert a denial of the existence of individuals who feel pride or are comfortable in their Turkishness, nor a questioning of their identity.
Once an area had been conquered, and hostilities had ceased, agricultural villagers may have felt little inconvenience with the arrival of these pastoralists, since they occupied different ecological zones within the same territory. Turkic pastoralists, however, made up only a small minority of the population, and the gradual Turkification of Anatolia was due to the conversion of Christians to Islam, and their adoption of the Turkish language. The reasons for this conversion were first, the weak hold Greek culture had on much of the population, and second, the desire by the conquered population to "retain its property or else to avoid being at a disadvantage in other ways. One mark of the progress of Turkification was that by the 1330s, place names in Anatolia had changed from Greek to Turkish. The Ottomans had relative tolerance for different cultures and religions. The men of the ruling dynasty took wives from various ethnic groups and thus were of mixed ethnic and cultural heritage.
The word Türk was a derogatory term until the late 19th century, referring to backwards Anatolian nomads or peasants. The Ottoman elite identified themselves as Sunni Muslims and Ottomans, never as Turks. In the late 19th century, as European ideas of nationalism were adopted by the Ottoman elite, and as it became clear that the Turkish-speakers of Anatolia were the most loyal supporters of Ottoman rule, the term Türk took on a much more positive connotation. During Ottoman times, the millet system defined communities on a religious basis, and a residue of this remains in that Turkish villagers will commonly consider as Turks only those who profess the Sunni faith, and will consider Turkish-speaking Jews, Christians, or even Alevi Muslims to be non-Turks. On the other hand, Kurdish-speaking or Arabic-speaking Sunnis of eastern Anatolia are often considered to be Turks. The imprecision of the appellation Türk can also be seen with other ethnic names, such as Kürt, which is often applied by western Anatolians to anyone east of Adana, even those who speak only Turkish. Thus, the category Türk, like other ethnic categories popularly used in Turkey, does not have a uniform usage. In recent years, centrist Turkish politicians have attempted to redefine this category in a more multi-cultural way, emphasizing that a Türk is anyone who is a citizen of the Republic of Turkey. Now article 66 of the Turkish Constitution defines a "Turk" as anyone who is "bound to the Turkish state through the bond of citizenship".
The region of the Anatolia represents an extremely important area with respect to ancient population migration and expansion, and the spread of the Caucasian, Indo-European and Altaic languages, as well as the extiction of the local Anatolian languages. During the late Roman Period, prior to the Turkic invasion, the population of Anatolia had reached an estimated level of over 12 million people . The extent to which gene flow from Central Asia has contributed to the current gene pool of the Turkish people, and the role of the 11th century invasion by Turkic peoples, has been the subject of several studies. These studies conclude that local Anatolian groups are the primary source of the present-day Turkish population. DNA results suggests the lack of strong genetic relationship between the Mongols and the Turks despite the historical relationship of their languages.
Anatolians do not significantly differ from other Mediterranean populations, indicating that while the Asian Turks carried out an invasion with cultural significance (language and religion), the genetic significance is only weakly detectable. Recent genetic research has suggested the local Anatolian origins of the Turks and that genetic flow between Turks and Asiatic peoples might have been slight. These findings are consistent with a model in which the Turkic languages, originating in the Altai-Sayan region of Central Asia and northwestern Mongolia, were imposed on the indigenous peoples with relatively little genetic admixture, possible example of elite cultural dominance - driven linguistic replacement. These observations also may be explained by Anatolia having the lowest migrant/resident ratio at the time of Turkic migrations. Analysis suggested that, genetically, Anatolians are more closely related also with the Balkanian populations than to the Central Asian populations. Analogical results have been received in neighbouring Caucasus region by testing Armenian and Turkic speaking Azerbaijanian populations, therefore representing language replacements, possibly via elite dominance involving primarily male migrants. As concussion, today the major DNA components in Anatolian population are shared with European and neighboring Near Eastern populations and contrast with only a minor share of haplogroups related to Central Asian, Indian and African affinity, which supports the language replacement hypothesis in the region.