The Windward Islands are called such because they were more windward to sailing ships arriving in the New World than the Leeward Islands, given that the prevailing trade winds in the West Indies blow east to west. The trans-Atlantic currents and winds that provided the fastest route across the ocean brought these ships to the rough dividing line between the Windward and Leeward islands. Dominica is the dividing line between the Windward and Leeward islands. Guadeloupe and the islands to the south were designated "Windward Islands". Later on, all islands north of Martinique became known as the Leeward Islands. Vessels in the Atlantic slave trade departing from the AfricanGold Coast and Gulf of Guinea would first encounter the southeasternmost islands of the Lesser Antilles in their west-northwesterly heading to final destinations in the Caribbean and North and Central America. The chain of islands forms a part of the easternmost boundary of the Caribbean Sea. Most of the islands of the present "Windward Islands" were once ruled by France and considered to be part of the French Antilles.