ditch systems. Few hill forts have been substantially excavated in the modern era, Danebury being a notable exception, with 49% of its total surface area studied. However, it appears that the "forts" were also used for domestic purposes, with examples of food storage, industry and occupation being found within their earthworks. On the other hand, they may have been occupied only intermittently, as it is difficult to reconcile permanently-occupied hill forts with the lowland farmsteads and their roundhouses found during the 20th century, such as at Little Woodbury and Rispain Camp. Many hill forts are not in fact "forts" at all and demonstrate little or no evidence of occupation. The development of hill forts may have occurred from greater tensions that arose between the better-structured and more populous social groups. Alternatively, there are suggestions that in the latter phases of the Iron Age, the structures simply indicate a greater accumulation of wealth and a higher standard of living although any such shift is invisible in the archaeological record for the Middle Iron Age, when hill forts come into their own. In that regard, they may have served as wider centres used for markets and social contact. Either way, during the Roman occupation the evidence suggests that as defensive structures, they proved to be of little use against concerted Roman attack. Suetonius comments that Vespasian captured more than 20 "towns" during a campaign in the West Country in 43 AD, and there is some evidence of violence from the hill forts of Hod Hill and Maiden Castle in Dorset from this period. Some hill forts continued as settlements for the newly-conquered Britons. Some were also reused by later cultures, such as the Saxons in the early medieval period. People of Iron Age Britain "Britain, we are told, is inhabited by tribes which are autochthonous and preserve in their ways of living the ancient manner of life. They use chariots, for instance, in their wars, even as tradition tells us the old Greek heroes did in the Trojan War." Diodorus Siculus, Bibliotheca historica. Celtic movement from Continent The Roman historian Tacitus suggested that the Britons were descended from people who had arrived from the Continent, and he compared the Caledonians (in modern-day Scotland) to their Germanic neighbours, the Silures of Southern Wales to Iberian settlers and the inhabitants of Southeastern Britannia to Gaulish tribes. That migrationist view long informed later views of