More important than the Celts and the Romans for the development of the English language, though, was the succession of invasions from continental Europe after the Roman withdrawal. No longer protected by the Roman military against the constant threat from the Picts and Scots of the North, the Celts felt themselves increasingly vulnerable to attack. Around 430AD, the ambitious Celtic warlord Vortigern invited the Jutish brothers Hengest and Horsa (from Jutland in modern-day Denmark), to settle on the east coast of Britain to form a bulwark against sea raids by the Picts, in return for which they were "allowed" to settle in the southern areas of Kent, Hampshire and the Isle of Wight.