The struggle with Spain was now terminated by a treaty which recognised the independence of Portugal; but _Brazil_, though having nothing to fear from external enemies, was troubled with foes from within its own borders, who attacked the interior settlements of _Bahia_ and the islands. Whole families were cut off before succour could reach them; whilst many slaves were killed at their field-work. As a remedy, guards of troops were assigned to the outlying colonists; but, whilst the soldiers were often transfixed by arrows coming from invisible enemies, they for years never once had an opportunity of returning the injury. Such settlers as did not take refuge in the islands were compelled to convert their settlements into small forts. At length the death at the hands of the savages of Manoel Barbosa, who was in command of the garrison at _Cayru_, induced the governor of _Bahia_ to complete the conquest of the country in the interior, a task which was confided to a body of _Paulistas_ under Joam Amaro. This war having been pronounced just and lawful, all prisoners taken in its course became slaves. The expedition under Amaro is said to have been composed of such a body of experienced man-hunters as, happily, no other locality in the world could supply, many of his men being trained Indians. They proceeded westward to the _San Francisco_ river, turning then to the northward. The prisoners captured were sent to the capital in such numbers that their price fell to twenty _cruzados_ each;[5] but the greater number were so short-lived that they were considered dear even at that price. Amaro did his work thoroughly, exploring the country in all parts, and so clearing it of savages that they were not again heard of for many years. He was rewarded with the lordship of a town which he founded, and which took his name. It was at this time that the fertile province of _Piauhi_ first became known. Its discovery was due to the possessor of a grazing estate to the north of the _San Francisco_, called after Domingos Affonso. As the interior of _Pernambuco_ is subject to droughts, this settler sent out his people to explore more desirable grazing regions inland. In _Piauhi_ he found a territory abounding in the richest pasture, and not subject to a like visitation. Whilst exploring the interior, Affonso met with a party of _Paulistas_, who engaged with him in completing the conquest of the country, which was of so inviting a nature that it was soon covered with settlers. [Sidenote: 16676.]