His fluency in Arabic and Castilian allowed him to perform undercover operations in Spain as well as undertaking secret negotiations in Morocco on behalf of King John II of Portugal.

[4] These successful exploits prodded the King to send him and Afonso de Paiva to undertake a mission of exploration in the Near East and the adjoining regions of Asia and Africa, with the special assignment to learn where cinnamon and other spices could be found, as well as of discovering the land of legendary Prester John, by overland routes.

Covilhã and Paiva were briefed by the Bishop of Tangiers and two Jewish mathematicians, Rodrigo and Moisés, who were prominent members of the commission which advised the Portuguese government to reject the proposals of Christopher Columbus.

Meanwhile, King John II of Portugal had sent two Portuguese Jews: Rabbi Abraham of Beja and José Sapateiro, a shoe-maker of Lamego with letters for Covilhã and Paiva outlining further instructions.

Through José Sapateiro, Covilhã replied with an account of his Indian and African journeys, and of his observations on the cinnamon, black pepper and clove trade at Calicut, together with advice as to the ocean way to India.

When the Portuguese embassy under Rodrigo de Lima, which included Ethiopian ambassador Mateus and missionary Francisco Álvares, entered Ethiopia in 1520, Covilhã wept with joy at the sight of his fellow-countrymen.

Álvares, who professed to know him well, and to have heard the story of his life, both in confession and out of it, praises his power of vivid description as if things were present before him, and his extraordinary knowledge of all the spoken languages of Christians, Muslims and Gentiles.

[9] Covilhã's extensive travels in the medieval world saw him visit the modern day states of Spain, Morocco, Italy, Greece, Egypt, Sudan, Yemen, Saudi Arabia, India, Mozambique, Iran, Eritrea and Ethiopia.

From their base in the city of Fremona, the Jesuits were able to convert the Ethiopian Emperors Za Dengel and Susenyos I to the faith in the 17th century but this resulted in a series of devastating rebellions and revolts against Catholic rule.