The rivers forming this system are the Maranon from Puerto Limon to Tabatinga on the Brazilian frontier (484 m.), the Japura, Putumayo, Javary, Napo, Tigre, Huallaga, Ucayali, Pachitea, Jurua, Purus, Acre, Curaray and Aguarico all navigable over parts of their courses for steamers of 4 to 8 f t.
At Canaria, the high land commences and continues as far as Tabatinga, and thence up stream.
The town of Manaos, at the mouth of the Rio Negro, had from l000 to 1500 population; but all the remaining villages, as far up as Tabatinga, on the Brazilian frontier of Peru, were wretched little groups of houses which appeared to have timidly effected a lodgment on the river bank, as if they feared to challenge the mysteries of the sombre and gigantic forests behind them.
At first the navigation was principally confined to the main river; and even in 1857 a modification of the government contract only obliged the company to a monthly service between Path and Manaos, with steamers of 200 tons cargo capacity, a second line to make six round voyages a year between Manaos and Tabatinga, and a third, two trips a month between Path and Cameta.
The government of Brazil, constantly pressed by the maritime powers and by the countries encircling the upper Amazon basin, decreed, on the 31st of July 1867, the opening of the Amazon to all flags; but limited this to certain defined points - Tabatinga, on the Amazon; Cameta, on the Tocantins; Santarem, on the Tapajos; Borba, on the Madeira; Manaos, on the Rio Negro; the decree to take effect on the 7th of September of the same year.