
Remnants of the Felix Romuliana Imperial Palace, a UNESCO World Heritage Site
Source: Pudelek (Marcin Szala), CC BY-SA 3.0 RS
Archaeological evidence of Paleolithic settlements on the territory of present-day Serbia is scarce. The oldest such evidence is a fragment of a human jaw, found in the village of Sicevo (Mala Balanica), which is believed to be up to 525,000–397,000 years old.
Approximately around 6,500 years BC, during the Neolithic, the Starcevo and Vinca cultures existed in the region of modern-day Belgrade. They dominated much of Southeastern Europe, (as well as parts of Central Europe and Asia Minor). Several important archaeological sites from this era, including Lepenski Vir and Vinca-Belo Brdo, are near the banks of the Danube

Lepenski Vir idol, 7000 BC

Vinca culture figurine, 4000–4500 BC.
During the Iron Age, local tribes of Triballi, Dardani, and Autariatae were encountered by the Ancient Greeks during their cultural and political expansion into the region, from the 5th up to the 2nd century BC. The Celtic tribe of Scordisci settled throughout the area in the 3rd century BC. It formed a tribal state, building several fortifications, including their capital at Singidunum (present-day Belgrade) and Naissos (present-day Nis).
The Romans conquered much of the territory in the 2nd century BC. In 167 BC the Roman province of Illyricum was established; the remainder was conquered around 75 BC, forming the Roman province of Moesia Superior; the modern-day Srem region was conquered in 9 BC; and Backa and Banat in 106 AD after the Dacian Wars. As a result of this, contemporary Serbia extends fully or partially over several former Roman provinces, including Moesia, Pannonia, Praevalitana, Dalmatia, Dacia and Macedonia.
The chief towns of Upper Moesia (and broader) were: Singidunum (Belgrade), Viminacium (now Old Kostolac), Remesiana (now Bela Palanka), Naissos (Nis), and Sirmium (now Sremska Mitrovica), the latter of which served as a Roman capital during the Tetrarchy. Seventeen Roman Emperors were born in the area of modern-day Serbia, second only to contemporary Italy. The most famous of these was Constantine the Great, the first Christian Emperor, who issued an edict ordering religious tolerance throughout the Empire.
When the Roman Empire was divided in 395, most of Serbia remained under the Eastern Roman Empire. At the same time, its northwestern parts were included in the Western Roman Empire. By the 6th century, South Slavs migrated into the European provinces of the Byzantine Empire in large numbers. They merged with the local Romanised population that was gradually assimilated.

Mosaic of Greek god Dionysus, Felix Romuliana - PhotoCredit: pinterest; Dionis, Gamzigrad