differentiating literal mercenaries from foreign vassals, brought to the battlefield through pacts or hostages instead of payment, is often difficult in ancient chronicles. similarly, the exact procedence of spanish mercenaries are difficult to sort out either every time they are mentioned, as the terms used to refer to inhabitants of the iberian peninsula are frequently vague, often using the generic "iberian" to mean not only the coastal iberian tribes, but any other people of hispania. however, there is evidence that hispania developed as a rich source of mercenary work during the early iron age. the reasons for this were mainly economic, as departing from the native tribe and serving in another, wealthier faction was a way for economically disadvantaged youth to escape poverty in their local lands, which were commonly subjected to sharp economic inequality. the main examples were found in lusitania and celtiberia, where cultivable terrains was concentrated among a few landowners, leaving mercenary life as the only alternative to banditry. however, the long history of tribal warfare and warrior culture between tribes in hispania cannot be discarded as another factor in their choice. natives from balearic islands and mountain folk from cantabria were also recognized to have a strong mercenary tradition.