Helmet of Ciumești

The appearance of Celts in Transylvania can be traced to the later La Tène period (c. 4th century BC). Excavation of the great La Tène necropolis at Apahida, Cluj County, by S. Kovacs at the turn of the 20th century revealed the first evidence of Celtic culture in Romania. The 3rd–2nd century BC site is remarkable for its cremation burials and chiefly wheel-made funeral vessels.

A historical timeline of the Celts of Transylvania can be derived from archaeological finds at La Tène, but there are almost no ancient records that allow reconstruction of political events in the area. The Celts exercised politico-military rule over Transylvania between the 4th and 2nd century BC and brought with them a more advanced iron-working technology. They were also responsible for the spread of the potter's wheel into a much wider area than the one they occupied.

Large areas of ancient Dacia, which were populated early in the First Iron Age by Thracian people, were affected by a massive migration of Iranian Scythians moving east to west during the first half of the first millennium BC. They were followed by a second equally large wave of Celts migrating west to east. Celts arrived in northwestern Transylvania in around 400–350 BC as part of their great migration eastwards. When Celtic warriors first penetrated these territories, the group seem to have merged with the domestic population of early Dacians and assimilated many Hallstatt cultural traditions.

The second half of the 4th century BC saw the Middle La Tène Celtic culture emerge in north-western and central Dacia, a development reflected especially in burials of the period. Celtic artifacts dating to this time have been discovered at Turdaş, Haţeg and Mediaş in modern-day Romania. By 1976, the number of Celtic sites found in Transylvania had reached about 150, indicating a significant La Tène population surpassed only by the Dacians. These sites are mostly cemeteries. Archaeological investigations have highlighted several warrior graves with military equipment, suggesting that an elite Celtic military force penetrated the region.

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