In response to the need for a new route to Asia, by the 1480s, Christopher and his brother Bartholomew had developed a plan to travel to the Indies (then construed roughly as all of southern and eastern Asia) by sailing directly west across what was believed to be the singular "Ocean Sea," the Atlantic Ocean. By about 1481, Florentine cosmographer Paolo dal Pozzo Toscanelli sent Columbus a map depicting such a route, with no intermediary landmass other than the mythical island of Antillia. In 1484 on the island of La Gomera in the Canaries, then undergoing conquest by Castile, Columbus heard from some inhabitants of El Hierro that there was supposed to be a group of islands to the west.