The history of Vanuatu before European colonisation is mostly obscure because of the lack of written sources up to that point, and because only limited archaeological work has been conducted; Vanuatu's volatile geology and climate is also likely to have destroyed or hidden many prehistoric sites. However, archaeological evidence gathered since the 1980s supports the theory that the Vanuatuan islands were first settled about 3,000 years ago, in the period roughly between 1,100 BC and 700 BC. These were almost certainly people of the Lapita culture. The formerly widespread idea that Vanuatu might have been only marginally affected by this culture was rendered obsolete by the evidence uncovered in recent decades at numerous sites on most of the islands in the archipelago, ranging from the Banks Islands in the north to Aneityum in the south.