Prehistoric and historic remains testify to the human occupation of the River Madeira basin and the social lives of its inhabitants. Reports from travelers who sailed on the Madeira in the 17th century describe an enormous cultural diversity which was systematically pushed aside as colonization began.
Archeologists have found remnants of pre-ceramic occupation on the Upper Madeira in the areas where the Santo Antônio and Jirau HEPS are located. These include a splintered pointed projectile which indicates the presence of groups of hunter gatherers who may have inhabited the region more than 10,000 years ago.
Rock inscriptions found on the Madeira always arouse the curiosity of visitors whether they are scientists or not. There are 21 registered archeological sites in the Santo Antônio area, two of which have rock inscriptions.
As well as the archeological sites, the Madeira basin also provides evidence of the historic periods of Rondônia. There are remains of small colonial encampments established from the 18th century along the Madeira. There are also signs of settlements by rubber tappers dating from the 19th century and beginning of the 20th century and from the time of the Second World War.