Muhacir, Macırlar, or Muhajir, is a term used to refer to an estimated 10 million Ottoman Muslim citizens (including Turks, Albanians, Bosniaks, Circassians, Crimean Tatars, and Pomaks) who emigrated to Anatolia from the late 18th century until the end of the 20th century.
Initially, approximately 5-7 million Muslim migrants from hostile regions arrived in Ottoman Anatolia from 1783 to 1914. The influx of migration during the late 19th century and early 20th century was due to the loss of almost all Ottoman territory during the Balkan War of 1912-13 and World War I. These Muhacirs, or refugees, saw the Ottoman Empire, and subsequently the Republic of Turkey, as a protective "motherland". Many of the Muhacir escaped to Anatolia as a result of the widespread persecution of Ottoman Muslims that occurred during the last years of the Ottoman Empire. Thereafter, with the establishment of the Republic of Turkey in 1923, a large influx of Turks, as well as other Muslims, from the Balkans, the Black Sea, the Caucasus, the Aegean islands, the island of Cyprus, the Sanjak of Alexandretta (Hatay), the Middle East, and the Soviet Union continued to arrive in the region, most of which settled in urban north-western Anatolia. By the 1930s migration accelerated as another two million Muslims settled in Turkey. The bulk of these immigrants were the Balkan Turks who faced harassment and discrimination in their homelands. New waves of Turks and other Muslims expelled from Bulgaria and Yugoslavia between 1951 and 1953 were followed to Turkey by another exodus from Bulgaria in 1983-89, bringing the total of immigrants to nearly ten million people. Today, between a third and a quarter of Turkey's population are the descendants of these Muhacirs.
The first wave of immigrants from Bulgaria occurred during the Russo-Turkish War (1828–1829) when around 30,000 Bulgarian Turks arrived in Turkey. The second wave of about 750,000 immigrants left Bulgaria during the Russo-Turkish War of 1877-78, but approximately one-fourth of them died on the way. More than 200,000 of the rest remained inside the present borders of Turkey whilst the others were sent to other parts of the Ottoman Empire. The aftermath of the war led to major demographic restructuring of the ethnic and religious make-up of Bulgaria. As a result of these migrations, the percentage of Turks in Bulgaria was reduced from more than one-third of the population immediately after the Russo-Turkish War to 14.2% in 1900. Substantial numbers of Turks continued to emigrate to Turkey during, and following, the Balkan Wars and the First World War, in accordance with compulsory exchange of population agreements between Greece, Bulgaria, and Turkey. By 1934 the Turkish population fell to 9.7% of Bulgaria’s total population and continued to fall during the subsequent decades.
Communist rule after the Second World War ended most emigration from Bulgaria, but further bilateral agreements were negotiated in the early 1950s and late 1960s to regulate the outflow of Bulgarian Turks. The heavy taxation, nationalisation of private minority schools, and measures against the Turkish culture in the name of the modernisation of Bulgaria, built up great pressure for the Turkish minority to emigrate and, when exit restrictions were relaxed in 1950, many ethnic Turks applied to leave. In August 1950 the Bulgarian government announced that 250,000 ethnic Turks had made applications to emigrate and pressured Turkey to accept them within three months. However, the Turkish authorities declared that the country could not accept these numbers in such a short time and closed its borders over the following year. In what was tantamount to an expulsion, pressure for ethnic Turks to leave continued, and by late 1951 some 155,000 Turks left Bulgaria. Most had abandoned their property or sold it at well below its value; most of these emigrants settled successfully primarily in the Marmara and Aegean regions, helped by the distribution of land and the provision of housing. In 1968 another agreement was reached between the two countries, which allowed the departure of relatives of those who had left up to 1951 to unite with their divided families, and another 115,000 people left Bulgaria for Turkey between 1968-78. .
The latest wave of Turkish emigration began with the mass exodus in 1989, known as the "big excursion", when the Bulgarian Turks fled to Turkey in order to escape a campaign of forced assimilation. This marked a dramatic culmination of years of tension among the Turkish community, which intensified with the Bulgarian government's assimilation campaign in the winter of 1985 that attempted to make ethnic Turks change their names to Bulgarian Slavic names. The campaign began with a ban on wearing traditional Turkish dress, and speaking the Turkish language in public places, followed by the forced name-changing campaign. By May 1989, the Bulgarian authorities began to expel the Turks; when the Turkish government's efforts to negotiate with Bulgaria for an orderly migration failed, Turkey opened its borders to Bulgaria on 2 June 1989. However, on 21 August 1989, Turkey reintroduced immigration visa requirements for Bulgarian Turks. It was estimated that about 360,000 ethnic Turks had left for Turkey, though more than a third subsequently returned to Bulgaria once the ban on Turkish names had been revoked in December 1989. Nonetheless, once the Bulgarian communist regime fell, and Bulgarian citizens were allowed freedom of travel again, some 218,000 Bulgarians left the country for Turkey. The subsequent emigration wave was prompted by continuously deteriorating economic conditions; furthermore, the first democratic elections in 1990 won by the renamed communist party resulted in 88,000 people leaving the country, once again, most of them being Bulgarian Turks. By 1992, emigration to Turkey resumed at a greater rate. However, this time they were pushed by economic reasons since the country’s economic decline affected especially ethnically mixed regions. The Bulgarian Turks were left without state subsidies or other forms of state assistance and experienced deep recession. According to the 1992 census, some 344,849 Bulgarians of Turkish origin had migrated to Turkey between 1989 and 1992, which resulted in significant demographic decline in southern Bulgaria.
Approximately 900,000 Caucasians immigrated to Anatolia due to intermittent Russian attacks from 1768 to 1917; about two-thirds of them remained, and the rest were sent to Amman, Damascus, Aleppo, and Cyprus.
From 1771 until the beginning of the 19th century approximately 500,000 Crimean Tatars arrived in Anatolia.
The first wave of immigration from Cyprus occurred in 1878 when the Ottomans were obliged to lease the island to Great Britain; at that time, 15,000 Turkish Cypriots moved to Anatolia. The flow of Turkish Cypriot emigration to Turkey continued in the aftermath of the First World War, and gained its greatest velocity in the mid-1920s, and continued, at fluctuating speeds till the Second World War. Economic motives played an important part as conditions for the poor in Cyprus during the 1920s were especially harsh. Enthusiasm to emigrate to Turkey was inflated by the euphoria that greeted the birth of the newly established Republic of Turkey and later of promises of assistance to Turks who emigrated. A decision taken by the Turkish Government at the end of 1925, for instance, noted that the Turks of Cyprus had, according to the Treaty of Lausanne, the right to emigrate to the republic, and therefore, families that so emigrated would be given a house and sufficient land. The precise number of those who emigrated to Turkey is a matter that remains unknown. The press in Turkey reported in mid-1927 that of those who had opted for Turkish nationality, 5,000–6,000 Turkish Cypriots had already settled in Turkey. However, many Turkish Cypriots had already emigrated even before the rights accorded to them under the Treaty of Lausanne had come into force.
St. John-Jones tried to accurately estimate the true demographic impact of Turkish Cypriot emigration to Turkey. He supposed that:
"[I]f the Turkish-Cypriot community had, like the Greek-Cypriots, increased by 101 per cent between 1881 and 1931, it would have totalled 91,300 in 1931 – 27,000 more than the number enumerated. Is it possible that so many Turkish-Cypriots emigrated in the fifty-year period? Taken together, the considerations just mentioned suggest that it probably was. From a base of 45,000 in 1881, emigration of anything like 27,000 persons seems huge, but after subtracting the known 5,000 of the 1920s, the balance represents an average annual outflow of some 500 – not enough, probably, to concern the community’s leaders, evoke official comment, or be documented in any way which survives today".
By August 31, 1955, a statement by Turkey's Minister of State and Acting Foreign Minister, Fatin Rüştü Zorlu, at the London Conference on Cyprus, stated that:
Consequently, today  as well, when we take into account the state of the population in Cyprus, it is not sufficient to say, for instance, that 100,000 Turks live there. One should rather say that 100,000 out of 24,000,000 Turks live there and that 300,000 Turkish Cypriots live in various parts of Turkey.
The immigration of the Turks from Greece started in the early 1820s upon the establishment of an independent Greece in 1829. By the end of World War I approximately 800,000 Turks had immigrated to Turkey from Greece. Then, in accordance with the 1923 Treaty of Lausanne, under the 1923 Convention Concerning the Exchange of Greek and Turkish Populations, Greece and Turkey agreed to the compulsory exchange of ethnic populations. The term "Mübadil" was used to refer specifically to this migration. Between 350,000 and 500,000 Muslim "Turks" emigrated from Greece to Turkey, and about 1.2 million Orthodox Christian "Greeks" from Turkey moved to Greece. "Greek" and "Turkish" was defined by religion rather than linguistically or culturally. According to Article 1 of the Convention "…There shall take place a compulsory exchange of Turkish nationals of the Greek Orthodox religion established in Turkish territory, and of Greek nationals of the Muslim religion established in Greek territory. These persons shall not return to live in Turkey or Greece without the authorization of the Turkish government or of the Greek government".
An article published in The Times on December 5, 1923, stated that:
"…This transfer of populations is made especially difficult by the fact that few if any of the Turks in Greece desire to leave and most of them will resort to every possible expedient to avoid being sent away. A thousand Turks who voluntarily emigrated from Crete to Smyrna have sent several deputations to the Greek government asking to be allowed to return. Groups of Turks from all parts of Greece have submitted petitions for exemption. A few weeks ago, a group of Turks from Crete came to Athens with a request that they be baptized into the Greek church and thus be entitled to consideration as Greeks. The government however declined to permit this evasion."
The only exclusions from the forced transfer were the Greeks living in Constantinople (Istanbul) and the Turks of Western Thrace. The remaining Turks living in Greece have since continuously emigrated to Turkey, a process which has been facilitated by Article 19 of the Greek Nationality Law which the Greek state has used to deny re-entry of Turks who leave the country, even for temporary periods, and deprived them of their citizenship. Since 1923, between 300,000 and 400,000 Turks of Western Thrace left the region, most of the went to Turkey.
Immigration from Romania to Anatolia dates back to the early 1800s when the Russian armies made advances into the region. During the Ottoman period, the greatest waves of immigration took place in 1826 when approximately 200,000 people arrived in Turkey and then in 1878-1880 with 90,000 arrivals. Following the Republican period, an agreement made, on September 4, 1936, between Romania and Turkey allowed 70,000 Romanian Turks to leave the Dobruja region for Turkey. By the 1960s, inhabitants living in the Turkish exclave of Ada Kaleh were forced to leave the island when it was destroyed in order to build the Iron Gate I Hydroelectric Power Station, which caused the extinction of the local community through the migration of all individuals to different parts of Romania and Turkey.
Immigration from Yugoslavia started in the 1800s as a consequence of the Russian-supported Serb rebellions. Approximately 150,000 Turks immigrated to Anatolia in 1826, and then, in 1867, a similar number of Turks moved to Anatolia. In 1862–67 Muslim exiles from the Principality of Serbia settled in the Bosnia Vilayet. Upon the proclamation of the Republic of Turkey, 350,000 Turks arrived in Turkey between 1923 and 1930. An additional 160,000 people immigrated to Turkey after the establishment of Communist Yugoslavia from 1946 to 1961. Since 1961, immigrants from that Yugoslavia amounted to 50,000 people.