Parts of Scotland were also inhabited from an early time by the Picts, whose Pictish language was completely separate from Celtic and probably not an Indo-European language at all.The Pictish language and culture was completely wiped out during the Viking raids of the 9th Century AD , and the remaining Picts merged with the Scots. Further waves of Celtic immigration into Britain, particularly between 500 BC and 400 BC but continuing at least until the Roman occupation, greatly increased the Celtic population in Britain, and established a vibrant Celtic culture throughout the land