The Celtiberians were a group of Celts and Celticized peoples inhabiting an area in the central-northeastern Iberian Peninsula during the final centuries BC. They were explicitly mentioned as being Celts by several classic authors (e.g. Strabo). These tribes spoke the Celtiberian language and wrote it by adapting the Iberian alphabet, in the form of the Celtiberian script. The numerous inscriptions that have been discovered, some of them extensive, have allowed scholars to classify the Celtiberian language as a Celtic language, one of the Hispano-Celtic (also known as Iberian Celtic) languages that were spoken in pre-Roman and early Roman Iberia. Archaeologically, many elements link Celtiberians with Celts in Central Europe, but also show large differences with both the Hallstatt culture and La Tène culture.
There is no complete agreement on the exact definition of Celtiberians among classical authors, nor modern scholars. The Ebro river clearly divides the Celtiberian areas from non-Indo-European speaking peoples. In other directions, the demarcation is less clear. Most scholars include the Arevaci, Pellendones, Belli, Titti and Lusones as Celtiberian tribes, and occasionally the Berones, Vaccaei, Carpetani, Olcades or Lobetani.
In 195 BC, part of Celtiberia was conquered by the Romans, and by 72 BC the entire region had become part of the Roman province of Hispania Citerior. The subjugated Celtiberians waged a protracted struggle against the Roman conquerors, staging uprisings in 195–193, 181–179, 153–151, and 143–133. In 105 BC, Celtiberian warriors drove the Germanic Cimbri from Spain in the Cimbrian War (113–101 BC) and also played an important role in the Sertorian War (80–72 BC).