Celtic settlement of Southeast Europe in the context of "Sofia"

The Celts (/kɛlts/ KELTS, see pronunciation for different usages) or Celtic peoples (/ˈkɛltɪk/ KEL-tik) were a collection of Indo-European peoples in Europe and Anatolia, identified by their use of Celtic languages and other cultural similarities. Major Celtic groups included the Gauls; the Celtiberians and Gallaeci of Iberia; the Britons, Picts, and Gaels of Britain and Ireland; the Boii; and the Galatians. The interrelationships of ethnicity, language and culture in the Celtic world are unclear and debated; for example over the ways in which the Iron Age people of Britain and Ireland should be called Celts. In current scholarship, 'Celt' primarily refers to 'speakers of Celtic languages' rather than to a single ethnic group.

The history of pre-Celtic Europe and Celtic origins is debated. The traditional "Celtic from the East" theory, says the proto-Celtic language arose in the late Bronze Age Urnfield culture of central Europe, named after grave sites in southern Germany, which flourished from around 1200 BC. This theory links the Celts with the Iron Age Hallstatt culture which followed it (c. 1200–500 BC), named for the rich grave finds in Hallstatt, Austria, and with the following La Tène culture (c. 450 BC onward), named after the La Tène site in Switzerland. It proposes that Celtic culture spread westward and southward from these areas by diffusion or migration. A newer theory, "Celtic from the West", suggests proto-Celtic arose earlier, was a lingua franca in the Atlantic Bronze Age coastal zone, and spread eastward. Another newer theory, "Celtic from the Centre", suggests proto-Celtic arose between these two zones, in Bronze Age Gaul, then spread in various directions. After the Celtic settlement of Southeast Europe in the 3rd century BC, Celtic culture reached as far east as central Anatolia, Turkey.

The Scordisci (Ancient Greek: Σκορδίσκοι; Latin: Scordiscii, Scordistae) were an Iron Age cultural group who emerged after the Celtic settlement of Southeast Europe, and who were centered in the territory of present-day Serbia, at the confluence of the Savus (Sava), Dravus (Drava), Margus (Morava) and Danube rivers. They were historically notable from the beginning of the third century BC until the turn of the common era, and consolidated into a tribal state. At their zenith, their core territory stretched over regions comprising parts of present-day Serbia, Croatia, Bulgaria and Romania, while their influence spread even further. After the Roman conquest in the 1st century AD, their territories were included into the Roman provinces of Pannonia, Moesia and Dacia.

The Galatians (Ancient Greek: Γαλάται, romanized: Galátai; Latin: Galatae, Galati, Gallograeci; Greek: Γαλάτες, romanized: Galátes, lit. 'Gauls') were a Celtic people dwelling in Galatia, a region of central Anatolia in modern-day Turkey surrounding Ankara during the Hellenistic period. They spoke the Galatian language, which was closely related to Gaulish, a contemporary Celtic language spoken in Gaul.

The Galatians were descended from Celts who had invaded Greece in the 3rd century BC. The original settlers of Galatia came through Thrace under the leadership of Leogarios and Leonnorios c. 278 BC. They consisted mainly of three Gaulish tribes, the Tectosages, the Trocmii, and the Tolistobogii, but there were also other minor tribes. In 25 BC, Galatia became a province of the Roman Empire, with Ankara (Ancyra) as its capital.

The Autariatae or Autariatai (alternatively, Autariates; Ancient Greek: Αὐταριᾶται, Autariatai; Latin: Autariatae) were an Illyrian people that lived between the valleys of the Lim and the Tara, beyond the Accursed Mountains, and the valley of West Morava. Their territory was located inland from the Ardiaei and the Lake Skodra, extending east to the Dardani and north or northeast to the Triballi.

Along with the Ardiaei and the Dardani, the Autariatae are mentioned by Strabo in his Geographica as one of the three strongest Illyrian peoples in the pre-Roman Balkans. Following defeat during the Celtic invasions of the Balkans in the 4th century, a part of the Autariatae who remained in Bosnia adopted Celtic culture later in their history. Another part moved southwards and after an agreement with the Kingdom of Macedonia, 20,000 settled in the Parorbelian mountain range, in the borderlands between modern southeastern North Macedonia, northern Greece and southwestern Bulgaria.