 Appian wrote that the war broke out because this powerful city of the Celtiberian tribe of the Belli persuaded the people of some smaller towns to settle there and was building a circuit of walls seven kilometres long.It also forced the neighbouring Titti to join in.The Belli had agreed to the treaties Tiberius Sempronius Gracchus had made with tribes in Hispania at the end of the First Celtiberian War.