'Colonisation' means both the settling of a new population in a place and the takeover, often by conquest, of one country by another. This is well shown by the case of Ireland, with waves of settlement and centuries of rule by British overlords. By the time of the ancient Greeks, many islands of the Mediterranean had been settled, and the sea-faring Greeks and Phoenicians created new 'colonies' around the Aegean, in Malta, Sicily, Corsica and the Balearics. Islands offered stepping-stones between continents and beachheads for further colonial expansion. One of the first overseas conquests came with the takeover of the Canary Islands, off the African coast, by Castilian Spaniards in 1402, 90 years before Columbus set sail. Settlement was a most important aspect of imperialism in the islands. Some islands were unoccupied when Europeans and other conquerors claimed possession, but most had indigenous populations, the outcomes of centuries or millennia of migration, sometimes in multiple waves.