59 percent of the population of the FRY lived in urban areas. The largest cities are Belgrade, the federal capital and the capital of Serbia; Novi Sad, a commercial center; Niš, a transportation and industrial center; Kragujevac, a manufacturing center; and Podgorica, the capital of Montenegro. As a result of the wars following the collapse of the former Yugoslavia, about 646,000 refugees fled to Serbia and Montenegro from Croatia and Bosnia. Many settled in Belgrade or Serbia’s northern province of Vojvodina.

Cleavages among southern Slav tribes developed over time, particularly after the establishment in the 4th century AD of the north-south “Theodosian Line” demarcating the eastern and western segments of the Roman Empire. Organization of the Christian church subsequently was based on this division. Missionaries from Rome converted Slavic tribes in the west to Roman Catholicism (these tribal groups becoming progenitors of the Slovenes and Croatians), while missionaries from Constantinople converted ancestors of Serbs and Montenegrins to Eastern Orthodoxy.