Having sprung up probably in the 6th century, it was populated, round about the year one thousand, by a group of nobles from the Maritime Republic of Amalfi who had rebelled against the authority of the Doge. The rebels made a good choice when choosing the site in which to built their refuge: Ravello rises in an easily defendable position. The city quickly prospered, thanks in particular to the flourishing wool-spinning mill, known in olden times as the "Celendra", that on the 23rd of April 1292 was conceded to Bishop Giovanni Allegri by King Charles Il of Anjou, to provident agriculture and to the intense trade exchange carried out on the Mediterranean sea routes, especially with the Arabs and Byzantines. In 1137 Bernardo da Chiaravalle described the city as "...ancient, well fortified and impregnable, as well as being opulent it is so beautiful that it can easily be numbered among the first and most noble cities ...".