It is to be recollected that the interior of South America is the least known of any of the continents at the present time. Large areas of territory are practically unexplored. The backward state of the Amazon Valley is largely due to the fact that during three hundred years of Portuguese dominion it was closed commercially to the outside world. Slave-raiding by the Portuguese and the Brazilians went on unchecked. The colonists even fought against and destroyed the Jesuit missions which the devout and humane of their priests had established. The whole valley has existed under a dark cloud ever since the time when, in 1540, the first white man, Orellana, Pizarro's lieutenant, descended the Napo, Marañon, and Amazon from Quito to the Atlantic Ocean. In 1638 Pedro de Texiera performed his great feat of ascending the Amazon from the Atlantic to Quito, and descending it again in 1639, one of the most noteworthy explorations in history. Exaggerations of Indian savagery and dangers of climate have deterred settlers in later times. As for the Putumayo region, it was practically unknown until the last decade of the nineteenth century. The name "Amazon" was probably a result of the experiences of Orellana and his followers, who were attacked by a tribe of Indians, the Nahumedes, on the river of the same name, whose long hair and dress of chemises or shirts caused the explorers to think their attackers were women-warriors, or "amazons." There is no proof of the existence of any empire of women in South America, although there is a legend bearing on the subject. The Putumayo River rises near Pasto, in the Andes of Colombia, and traverses a vast region which forms one of the least-known areas of the earth's surface. This river is nearly a thousand miles long, flowing through territory which is claimed both by Peru and Colombia, and enters the main stream of the Amazon in Brazil. The river crosses the equator in its upper portion. The notorious rubber-bearing region upon the Putumayo and its affluents, the Igaraparaná and the Caraparaná, lies within a square formed by the equator on the north, the 2nd parallel of latitude on the south, and the 72nd and 74th degrees of longitude west of Greenwich. Like most of the Amazon tributaries, the Putumayo and its two affluents are navigable throughout the greater part of their courses, giving access by water up to the base of the Andes; and the rubber traffic is carried out by means of steam-launches and canoes.