 By 1900, the population had fallen to 1 million and by the early 1980s it was less than 200,000.The first European to travel the length of the Amazon River was Francisco de Orellana in 1542.The BBC's "Unnatural Histories" presents evidence that Orellana, rather than exaggerating his claims as previously thought, was correct in his observations that a complex civilization was flourishing along the Amazon in the 1540s.