Bolama (Boulam, Bulama) island was discovered by the Portuguese in 1446 ; in the next year Nuno Tristao, explor ing the Rio Grande (and probably seeking slaves), was attacked by the Nalu and killed, together with many of his followers. In 1462 rights over this part of the Guinea coast were granted to the Cape Verdi islanders, who appear to have founded the "factories" at Cacheu. In the 17th and 18th centuries the sup plying of slaves to Brazil and Spanish America was a very flour ishing industry, Bissao becoming the chief port for this commerce. Dispossessed by Dutch, French, British and other rivals of all the rest of the Seignory of Guinea, Portuguese rule in this district was only effective on the coast—and even the islands had been left for long unoccupied. In the middle of the i9th century the extension of French authority in the hinterland, and claims by Great Britain to Bolama island and the adjacent mainland, seemed to threaten to reduce the Portuguese territory to very small proportions. However, the British claim was referred to the arbitration of the United States and President Grant's award (April 21, 1870) was in favour of Portugal. By a convention with France in May 1886 the inland frontiers were fixed mainly on arbitrary lines, the frontier being demarcated in 1902-05 by a Franco-Portuguese commission. Portugal had succeeded in re taining an area about twice the size of Wales. Meanwhile, in
1879, the country had ceased to be a dependency of the Cape Verdi islands and had been made a separate province under a governor. But most of the tribes were practically independent and in 1908 there was a rising of the Papel tribe on Bissao island, and of the other tribes on the mainland. Troops sent from Portugal succeeded in restoring order. Other risings and inter-tribal war fare followed, but not of so serious a character. The disestablish ment of the Church in 1912 greatly hindered the work of the missionaries, one of the most civilizing influences in the province, but in 1925 the Portuguese Government reversed its policy, restored to the missions their churches and schools, and gave them subsidies—the avowed object being to exert a national, i.e., Portuguese influence on the natives (this change applied to all the Portuguese colonies).
See J. E. Giraud, "La Guinee portugaise," in Bull. soc. geog. Mar seille, vol. xxix. (1905) ; A. L. de Fonseca, "Guine" in Bull. soc. geog. Lisboa, vol. xxiii. (1905) ; R. Wagner, "Portugiesische Guinea: Land and Leute," in Deutsche Rundschau, vol. xxvii. (19o5) ; E. de Vascon celes, As Cologias portuguesas (Lisbon, 1896-97) ; J. Machat, Les Rivieres du sud (Paris, 1906), in which are cited many papers dealing with Portuguese Guinea ; Portuguese Guinea, a British Foreign Office handbook (192o), and the Anuario Coloneal (Lisbon).