The Celtiberians were Celtic-speaking people of the Iberian Peninsula in the final centuries BC. These tribes or nation spoke the Celtiberian language. Extant tribal names include the Arevaci, Belli, Titti, Lusones, and Berones.
Archaeologically, the Celtiberians participated in the Hallstatt culture in what is now north-central Spain. The term Celtiberi appears in accounts by Diodorus Siculus, Appian and Martial who recognized intermarriage between Celts and Iberians after a period of continuous warfare, though Barry Cunliffe says 'this has the ring of guesswork about it'; Strabo just saw the Celtiberians as Celts and recognised them as a branch of the Celti. Pliny considers the Celts from Iberia to have migrated from the territory of Lusitania's Celtici which he appears to regard as the original seat of the whole Celtic population of the Iberian peninsula including the Celtiberians, on the ground of an identity of sacred rites, language, and names of cities.
The Celtiberian language is one of the Iberian Celtic languages that were spoken in pre-Roman and early Roman Iberia.
Read more about Celtiberians: History