 However, Cumbria appears not to have any of the so-called 'developed hillforts' (enlarged from earlier versions, around 3–7 ha in area, with multiple ditches and complex entrances), suggesting that few, if any, were still being used in the pre-Roman Iron Age, apparently having been abandoned.The abandonment of land and settlements noted above is probably explained by climate change.Between c. 1250 BCE and c. 800 BCE, the climate deteriorated to the extent that, in Cumbria, upland areas and marginal areas of cultivation were no longer sustainable.