The height of the chalk ridge and proximity to Poole Harbour and the south coast have made the hills of strategic importance. There are a number of Iron Age, Roman and Saxonarchaeological sites, such as Nine Barrow Down. At Corfe Castle the hills are broken twice leaving a steep round hill between the ridges on which stood a medieval castle, guarding the only easy route through the hills, until the English Civil War of the 17th century, when it was slighted.
Some of the ridge, around the village of Tyneham, near Lulworth, has been closed to the public for use by the army as a firing range. This has protected them from damage from farming and development, and these areas are now nature reserves. At the eastern end Ballard Down is a National Trustnature reserve which is managed for its calcareous grasslandhabitat.