TV Horizon - Season 39 Episode 18 : The Secret of El Dorado Horizon - Season 39 Episode 18 : The Secret of El Dorado 7.516/10 by 32 users In 1542, the Spanish Conquistador, Francisco de Orellana ventured along the Rio Negro, one of the Amazon Basin's great rivers. Hunting a hidden city of gold, his expedition found a network of farms, villages and even huge walled cities. At least that is what he told an eager audience on his return to Spain. The prospect of gold drew others to explore the region, but none could find the people of whom the first Conquistadors had spoken. The missionaries who followed a century later reported finding just isolated tribes of hunter-gatherers. Orellana's story seemed to be no more than a fanciful myth. When scientists came to weigh up the credibility of Orellana's words, they reached the same conclusion. As productive as the rainforest may appear, the soil it stands in is unsuited to farming. It is established belief that all early civilisations have agriculture at their hearts. Any major population centre will have connections with a system of intensive agriculture. If a soil cannot support crops sufficient to feed a large number of people, then that serves as an effective cap on the population in that area. Even modern chemicals and techniques have failed to generate significant food from Amazonian soil in a sustainable way . The thought that indigenous people could have survived in any number - let alone prospered - was dismissed by most scientists. Scientific consensus was sure that the original Amazonians lived in small semi-nomadic bands and that Orellana must have lied. Details Casts Posters Images Title Horizon - Season 39 Episode 18 : The Secret of El Dorado Alternative Titles BBC Horizon First Air Date 1964-02-04 Last Air Date 2024-07-22 Number of Episodes 1169 Number of Seasons 60 Genres Documentary, Networks BBC Two, Casts Plot Keywords , Episodes List Horizon Season 39 :Episode 1 Helike - The Real Atlantis Helike - The Real Atlantis 2002-01-10 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 2 Volcano Hell Volcano Hell 2002-01-17 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 3 Fatbusters Fatbusters 2002-01-24 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 4 The Lost Pyramids of Caral The Lost Pyramids of Caral 2002-01-31 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 5 Death of the Iceman Death of the Iceman 2002-02-07 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 6 Parallel Universes Parallel Universes 2002-02-14 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 7 The Dinosaur that Fooled the World The Dinosaur that Fooled the World 2002-02-21 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 8 The Fall of the World Trade Center The Fall of the World Trade Center 2002-03-07 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 9 Archimedes' Secret Archimedes' Secret 2002-03-14 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 10 The Mystery of the Jurassic The Mystery of the Jurassic 2002-03-28 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 11 Killer Lakes Killer Lakes 2002-04-04 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 12 The A6 Murder The A6 Murder 2002-05-16 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 13 The England Patient The England Patient 2002-05-23 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 14 Freak Wave Freak Wave 2002-11-14 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 15 Stone Age Columbus Stone Age Columbus 2002-11-21 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 16 Homeopathy: The Test Homeopathy: The Test 2002-11-26 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 17 The Day the Earth Nearly Died The Day the Earth Nearly Died 2002-12-05 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before. Horizon Season 39 :Episode 18 The Secret of El Dorado The Secret of El Dorado 2002-12-19 Horizon tells amazing science stories, unravels mysteries and reveals worlds you've never seen before.