Sandžak has a diverse and complex ethnic and religious composition, with significant Eastern Orthodox, Roman Catholic, and Sunni Muslim populations.

Six municipalities of Sandžak are in Serbia (Novi Pazar, Sjenica, Tutin, Prijepolje, Nova Varoš, and Priboj[15]), and seven in Montenegro (Pljevlja, Bijelo Polje, Berane, Petnjica, Rožaje, Gusinje, and Plav).

[20][21][23] The Islamization of Sandžak was otherwise caused by a number of factors, mainly economic, as Muslims didn't pay the devşirme tributes and jizya taxes.

[25] The second factor that contributed to the Islamization were migrations; a large demographic shift occurred after the Great Turkish War (1683–1699).

[26] The land abandoned by the Eastern Orthodox Serbs was settled by populations from neighbouring areas who either were or became Muslim in Sandžak.

[26] The third factor of Islamization was the geographical location of Sandžak, which allowed it to become a trade centre, facilitating conversions amongst merchants.

[33] Some members of the Albanian Shkreli and Kelmendi tribes began migrating into the lower Pešter and Sandžak regions at around 1700.

[35] Since the 18th century, many people originating from the Hoti tribe have migrated to and live in Sandžak, mainly in the Tutin area, but also in Sjenica.

[citation needed] This led to the displacement of many Slavic Muslims and Albanians, who migrated to Ottoman Turkey as muhajir.

[citation needed] After the war, Sandžak became a part of the newly formed State of Slovenes, Croats and Serbs.

[29] The region acted as a bridge between the Muslims in the West in Bosnia and Herzegovina and those in the East in Kosovo and North Macedonia.

[37] Additionally, the agrarian reform implemented in the Kingdom of Yugoslavia worsened their economic situation, leading to the emigration of Muslims from Sandžak to the Ottoman Empire.

[citation needed] In 1919, Serb forces attacked Albanian populations in Plav and Gusinje, which had appealed to the British government for protection.

Smaller groups of both Orthodox Serbs and Muslims organized after 1943 in the Yugoslav Partisan Anti-Fascist Council of the People's Liberation of Sandžak.

Albanian militia fought for inclusion in Greater Albania, while Ustaše formations wanted at least part of Sandžak to join the Bosnian Muslims of the Independent State of Croatia.

[46] The formal partition of Sandžak between Italian and German spheres of influence was largely ignored as local politics shaped control over the area.

Prijepolje which formally was within the Italian area of rule in Montenegro was in fact under the NDH-affiliated Sulejman Pačariz, while Novi Pazar in the German sphere was led by the Albanian nationalist Aqif Bluta.

[47] The Italian and German forces considered to enact population exchange from Sandžak to Kosovo to stop interethnic violence between Serbs and Albanians.

Peter Pfeiffer, diplomat of the Foreign Office of Germany warned that relocation plans would cause a great rift between the German army and Albanians and they were abandoned.

In 1943, Chetnik forces based in Montenegro conducted a series of ethnic cleansing operations against Muslims in the Bihor region of modern-day Serbia.

In May 1943, an estimated 5400 Albanian men, women and children in Bihor were massacred by Chetnik forces under Pavle Đurišić.

The memorandum was sent to Prime Minister Ekrem Libohova whom they asked to intervene so the region could be united to the Albanian kingdom.

[58] In January 1944, the Land Assembly of Montenegro and the Bay of Kotor claimed Sandžak as part of a future Montenegrin federal unit.

The AVNOJ explained that the Sandžak did not have a national basis for an autonomy and opposed crumbling of the Serbian and Montenegrin totality.

[37] The emigration of the Muslims to Turkey also continued, caused by the general underdevelopment of the region, disagreement with the communist authorities and the mistrust with the Serbs and Montenegrins, but also due to the nationalisation and expropriation of property.

[69] The last Yugoslav pre-war census of 1931 counted in Bijelo Polje, Prijepolje, Nova Varoš, Pljevlja, Priboj, Sjenica and Štavica a total population of 204,068.

[70] There were a larger presence of Albanians in Sandžak in the past, however due to various factors such as migration, assimilation, along with mixing, many identify as Bosniaks instead.

[27][71][72] Catholic Albanian groups which settled in Tutin and Pešter in the early 18th century were converted to Islam in that period.

[73] The Slavic dialect of Gusinje and Plav (sometimes considered part of Sandžak) shows very high structural influence from Albanian.

Religion in Sandžak is also as diverse as the ethnic composition, most of the Bosniaks being Muslim while a majority of the Serbs being Orthodox Christian.