The three main ethnic groups in present-day Bosnia and Herzegovina are Bosniak, Serb, and Croat, and languages are Bosnian, Serbian, and Croatian. Nationalities are Bosniak, Bosnian Serb, and Bosnian Croat. Religions include Muslim, Catholic, Protestant, and some others.

For the first centuries of the Christian era, Bosnia was part of the Roman Empire. After the fall of Rome, Bosnia was contested by Byzantium and Rome's successors in the west. Slavs settled the region in the 7th century, and the kingdoms of Serbia and Croatia split control of Bosnia in the 9th century. The 11th and 12th centuries saw the rule of the region by the kingdom of Hungary. The medieval kingdom of Bosnia gained its freedom around 1200 A.D. Bosnia remained independent until 1463, when Ottoman Turks conquered the region.

During Ottoman rule, many Bosnians converted from Christianity in favor of Islam. Bosnia was under Ottoman rule until 1878, when it was given to Austria-Hungary as a colony. While those living in Bosnia came under rule by the Austrian-Hungarian Empire, South Slavs in Serbia and elsewhere were calling for a South Slav state. World War I began when Serb nationalist Gavrilo Princip assassinated the Archduke Ferdinand in Sarajevo. Following the Great War, Bosnia became part of the South Slav state of Yugoslavia, only to be given to Nazi-puppet Croatia in World War II. During this time, many atrocities were committed against Jews, Serbs, and others who resisted the occupation.

Yugoslavia's unraveling was hastened by the rise of Slobodan Milosevic to power in 1986. Milosevic's embrace of Serb nationalism led to intrastate ethnic strife. Slovenia and Croatia both declared freedom from Yugoslavia in 1991. In February 1992, the Bosnian Government held a vote on freedom. Bosnia's parliament declared the republic's freedom on April 5, 1992. this move was opposed by Serb representatives who favored remaining in Yugoslavia. Bosnian Serbs, supported by neighboring Serbia, responded with armed resistance in an effort to partition the republic along ethnic lines to create a "greater Serbia." Full recognition of its freedom by the United States and most European countries occurred on April 7, and Bosnia-Herzegovina was admitted to the United Nations on May 22, 1992.

In March 1994, Muslims and Croats in Bosnia signed an agreement creating the Federation of Bosnia and Herzegovina. This narrowed the field of warring parties down to two. The conflict continued through most of 1995, ending with the Dayton Peace Agreement being signed on November 21, 1995. Bosnia and Herzegovina today consists of two entities -- the Muslim/Croat Federation of Bosnia and Herzegovina, which is largely Bosniak and Croat, and the Republika Srpska, which is primarily Serb.