There they separated. Paiva was to make his way directly to Ethiopian and Prester John, while Covilhã would go on to India. Paiva disappeared, but Covilhã finally reached Calicut and Goa on the southwestern shores of India, where he witnessed the prosperous trade in Arabian horses, spices, fine cottons, and precious stones. In February 1489 Covilhã took ship westward to Ormuz at the entrance to the Persian Gulf, then to the east African port of Sofala opposite Madagascar and back north to Cairo. Having completed his mission of assessing the European trade with India, he was eager to return home, but there in Cairo he encountered two Jewish emissaries from King John II who carried a letter instructing Covilhã, if he had not already done so, to proceed at once to the realm of Prester John to collect information and promote an alliance.

Unable to disobey his sovereign, Covilhã took up the mission, meanwhile sending to King John a momentous letter with all he had learned about Arab seafaring ant the commerce of India. In 1493, after a side trip to Mecca, six years after his departure from Portugal, he finally arrived in Ethiopia. In this Realm of Prester John, actually ruled by Alexander “Lion of the Tribe Judah, and King of Kings,” he became a Portuguese Marco Polo, so useful at court that the King would not let him leave. Convinced that we would never return home, Covilhã married an Ethiopian wife who bore him several children.

Meanwhile, Covilhã’s letter, which has not survived and which is known only secondhand, would have a powerful influence on the future of Portugal and Asia. For it appears to have informed King John II, from reports Covilhã had heard on the African coast, “that his [the king’s] caravels, which carried on trade in Guinea, navigating from land to land seeking the coast of this island [Madagascar] and Sofala, could easily penetrate into these Eastern seas and come to make the coast of Calicut, for there was sea everywhere.”

“The Portuguese Discoverers”, from “The Discoverers”, Daniel J. Boorstin, The National Board for the Celebration of Portuguese Discoveries, Lisbon, 1987