At this stage in the relation of the founding of the Portuguese dominion and influence over Africa some mention must be made of the part played during the 15th century by the Jews settled in Portugal. Badly as the Christians of Portugal treated the Jews, their existence in this western kingdom was not unbearable compared with the ferocious cruelty of the Spaniards; consequently during the 15th century the Jewish colonies in Portuguese cities increased considerably, and Jews even rose to a high position in the state. In return they established printing-presses, advanced education, and spread a knowledge of geography, astronomy, mathematics, classical history and medicine which was directly useful to the new school of Portuguese seamen-explorers, who mostly obtained their nautical instruments from the Jews. In short the Jews did much to create a Portuguese Empire beyond the seas; but they were subsequently treated with the grossest ingratitude and expelled from Portugal in the early 16th century, thousands of them being deported to Saõ Thomé in the Gulf of Guinea where they died of malarial fever. Before the rounding of the Cape of Good Hope by Diaz, the King of Portugal was convinced of the circumnavigability of Africa from the Atlantic into the Indian Ocean. Through enterprising Portuguese Jews (Abraham of Beja and Joseph of Lamego) who had travelled overland via Egypt and Syria to the Persian Gulf, he had heard that this was possible[56], and resolved to send two Portuguese officers, Pero de Covilham and Alfonso de Paiva, to travel to India by way of the Red Sea, and to find out all they could about the Christian King of Ethiopia and the Arab settlements on the East coast of Africa, and whether the King of Portugal might look for allies or friendly neutrals in this direction. Accordingly, in 1487, de Covilham and Paiva reached Egypt; and the former journeyed by the Red Sea to India, while the latter made for Abyssinia, but was killed on the way, near Suakin. Pero de Covilham, on his return journey from Southern India, visited the north coast of Madagascar and the settlement of Sofala, near the modern Beira (S.E. Africa). Thence he proceeded northwards, calling at all the Arab ports of East Africa till he once more re-entered the Red Sea. Returning to Cairo he learnt that his companion, Paiva, had been killed, but he met the two Jews, Abraham and Joseph. By the last-named he sent back word of his discoveries to King John II, and then starting off with Abraham of Beja he visited Mecca and Medina and finally landed at Zeila (N. Somaliland) and travelled to Abyssinia. The information sent back by de Covilham decided the despatch of an expedition under Vasco da Gama to pass round the Cape of Good Hope to the Arab colonies, and thence to India.