Between Ceuta in 1415 and Macao in 1999, the beginning and end of the empire, stretch six centuries, fifteen thousand nautical miles and two different models of colonisation. The last act of the Portuguese empire was in 1999 to hand over Macao to Chinese rule, after 450 years of a Portuguese presence marked by a way of life of mutual tolerance. Its rules changed over time, and many of them were scarcely written down; sometimes they were remote from official regulations, often they were shaped by local interests.

Ceuta was captured by King John I with an army of twenty thousand men carried in over two hundred ships. It was an enormous and formidable force for a country with a population of no more than a million: 2% of the population sailed to Ceuta. The expedition was for a long time explained as a crusade, or a means of glory for the princes Duarte and Pedro, and Henrique, Duke of Viseu(known to history as Henry the Navigator). The truth is that Ceuta was a trading centre in a strategic position to control the Strait of Gibraltar and communication between the Mediterranean and Atlantic. Its capture served the political interests of a new dynasty in need of international recognition, and opened opportunities of expansion for a small kingdom trapped between Castile and the sea.