João de Barros (1496 – 20 October 1570), called the Portuguese Livy, is one of the first great Portuguese historians, most famous for his Décadas da Ásia ("Decades of Asia"), a history of the Portuguese in India, Asia, and southeast Africa.
Educated in the palace of Manuel I of Portugal, he composed, at the age of twenty, a romance of chivalry, the Chronicle of the Emperor Clarimundo, in which he is said to have had the assistance of Prince John (afterwards King John III). Upon ascending the throne, he awarded Barros the captaincy of the fortress of St George of Elmina, to which he proceeded in 1522. In 1525, he obtained the post of treasurer of the India House, which he held until 1528.
To escape from an outbreak of bubonic plague in 1530 Barros moved from Lisbon to his country house near Pombal, where he finished a moral dialogue, Rho pica Pneuma, which was cheered by Juan Luís Vives. On his return to Lisbon in 1532 the king appointed Barros factor (agent) of the "Casa da Índia e da Mina" (House of India and Mina)— a position of great responsibility and importance at a time when Lisbon was the European center for the trade of the East. Barros proved a good administrator, displaying great industry and an honesty rare at the time, with the result that he made little profit compared to his predecessors, who had amassed fortunes.
At this time, John III, wishing to attract settlers to Brazil, divided it into captaincies and attributed to Barros that of Maranhão. Barros with two partners, prepared an armada of ten vessels, carrying nine hundred men each, which set sail in 1539. Owing to the ignorance of the pilots, the whole fleet was shipwrecked, which entailed serious financial loss to Barros. As a gesture of goodwill, Barros subsequently paid the debts of those who had perished in the expedition. During these years he had continued his studies in his leisure hours, and shortly after the Brazilian disaster he offered to write a history of the Portuguese in India, the Décadas da Ásia, which the king accepted. He began work forthwith, but, before printing the first part, he published a Portuguese grammar (1539) and some further moral Dialogues.
The first of the Décadas da Ásia ("Decades of Asia") appeared in 1552, and its reception was such that the king straightway charged Barros to write a chronicle of King Manuel. His many occupations, however, prevented him from undertaking this book, which was finally composed by Damião de Góis. The second Decade came out in 1553 and the third in 1563, but the fourth and final one was not published until 1615, long after the author’s death. His Decades contain the early history of the Portuguese in India and Asia and reveal careful study of Eastern historians and geographers, as well as of the records of his own country. They are distinguished by clearness of exposition and orderly arrangement. They are also lively accounts, for example describing the king of Viantana's killing of the Portuguese ambassadors to Malacca with boiling water and then throwing their bodies to the dogs. Diogo de Couto continued the Décadas, adding nine more, and a modern edition of the whole appeared in Lisbon in 14 vols. in 1778—1788 as Da Asia de João de Barros, dos feitos que os Portuguezes fizeram no descubrimento e conquista dos mares e terras do Oriente. The edition is accompanied by a volume containing a life of Barros by the historian Manoel Severim de Faria and a copious index of all the Decades. In January 1568 Barros retired from his remunerative appointment at the India House, receiving the rank of fidalgo together with a pension and other pecuniary emoluments from King Sebastian, and died on 20 October 1570.