the use of more substantial vessels, such as carracks, due to its unprecedented duration, about six months. On average, four carracks connected Lisbon to Goa carrying gold to purchase spices and other exotic items, but mainly pepper. From Goa, one carrack went on to Ming China in order to purchase silks. Starting in 1541, the Portuguese began trading with Japan, exchanging Chinese silk for Japanese silver; in 1550 the Portuguese Crown started to regulate trade to Japan, by leasing the annual "captaincy" to Japan to the highest bidder at Goa, in effect conferring exclusive trading rights for a single carrack bound for Japan every year. In 1557 the Portuguese acquired Macau to develop this trade in partnership with the Chinese. That trade continued with few interruptions until 1638, when it was prohibited by the rulers of Japan on the grounds that the ships were smuggling Catholic priests into the country. The Japanese called Portuguese carracks "Black Ships" (kurofune), referring to the colour of the ship's hulls. This term would eventually come to refer to any Western vessel, not just Portuguese. The Islamic world also built and used carracks, or at least carrack-like ships, in the Mediterranean and the Indian Ocean. Ottoman barca of Piri Reis' map is a deep-hulled ship with a tall forecastle and lateen sail in the mizzenmast. The harraqa (Saracen: karaque) was a type of ship used to hurl explosives or inflammable materials (firebomb in earthenware pots, naphtha, fire arrows). From the context of Islamic texts, there are 2 types of harraqa: The cargo ship and the smaller longship (galley-like) that was used for fighting. It is unclear whether the nomenclature harraqa has a connection with European carraca (carrack), or whether one influences the other. One Muslim harraqa named Mogarbina was captured by the Knights of St. John in 1507 from the Ottoman Turks and renamed Santa Maria. Gujarati ships are usually called naos (carracks) by the Portuguese. Gujarati naos operated between Malacca and the Red Sea, and were often larger than Portuguese carracks. The Bengalis also used carrack, sometimes called naos mauriscas (Moorish carracks) by the Portuguese. Arabs merchants of Mecca apparently used carracks too, since Duarte Barbosa noted that the Bengali people have "great naos after the fashion of Mecca". Famous carracks Santa María, in which Christopher Columbus made his first voyage to America in 1492. São Gabriel, flagship of Vasco da Gama, in the