emperor augustus decided that the circumnavigation of africa should also be attempted (in 1 bc). romans had two naval ouposts in the atlantic coast of africa: sala near present rabat and mogador in southern maroc (north of agadir). the island of mogador prospered for the local exploitation of purple (highly esteemed in imperial rome) from augustus until septimius severus times. augustus, based even in the discovery of a sunken merchant ship from southern spain in the djibuti area (done by his adoptive son gaius caesar when he sailed toward aden), wanted to organize an expedition from egypt to mogador and sala around africa.