One of the many Hollywood films that will hit theatres this year is "The Lost City of Z," in which a group of explorers set out to find a colleague who vanished in the Amazon rainforest.

Based on a true story, the movie stars Brad Pitt as Percy Fawcett, a world-famous British explorer who disappeared in 1925, during an expedition to find the mythical city of El Dorado, which Fawcett codenamed "Z" to keep his plans secret.

The premise of the movie, and its name, are taken from a book by David Grann, who retraced Fawcett's route through the Amazon to investigate what happened to him.

Along the way, Grann learned of a group of archeologists who are unearthing evidence that, just as Fawcett believed, there were indeed large communities thriving in the Brazilian rainforest before Europeans arrived.

As the evidence mounts, it's challenging conventional wisdom of the Amazon as a place so inhospitable it could only support small, nomadic tribes.

Instead it seems that large, complex societies may have tamed parts of the Amazon centuries before Spanish explorers sailed across the Atlantic. As that idea gains momentum, it's also gaining more attention beyond archaeological circles.

"There is now becoming, not just in the scientific and academic work but in the public world, a sense of the breadth of these discoveries," Grann told from New York. "They're transforming our view of what the Americas looked like before Columbus."

"It's finally kind of breaking through."

Turning point

Last month, a major archeological find was published in the British journal Antiquity. Using Google Earth and other satellite imagery, researchers found 260 geometrical shapes dug into a now-deforested 250-kilometre stretch of the upper Amazon basin.

"We know they're spread over this wide region and they display very similar construction techniques," said Denise Schaan, an archeologist from Brazil's University of Para who co-authored the study. "So if it was not a single people building them, they had a kind of culture or religion that was spread over that territory."

"We want to know who built these structures and for what reason," Schaan added, speculating that they could have been fortified villages or ceremonial centres.

Some of the earthworks may date as far back as AD 200, a millennium before the Incan empire was founded. As many as 60,000 people lived in or near the "perfect circles, rectangles and composite figures" carved into the ground, the researchers reported. And many were linked by bridges or "avenue-like" roads.

What's more, Schaan and her colleagues suspect there could be 10-times as many earthworks in surrounding areas, where the jungle is still standing.

The people who inhabited the sites disappeared around the same time that Spanish conquistadors ventured into South America, suggesting that diseases from Europe may have wiped them out.

A number of earlier discoveries suggest the Amazon was by no means virgin rainforest before the Age of Discovery began.

Archaeologists came across a series of 127 granite blocks on a Brazilian hilltop in 2006. Some of the blocks appear to be arranged astrologically, and may have been placed there as long as 2,000 years ago. The site has become know as the Stonehenge of the Amazon.

In 1996, American archaeologist Anna C. Roosevelt, a great-granddaughter of Theodore Roosevelt, found a series of 11,000-year-old wall paintings in a Brazilian cave. The paintings are so old they're challenging long-held assumptions about when the Americas were first settled and by whom.

More to come?

Technology may be one of the things driving these cascading discoveries. Grann says a lot of the archeologists who are investigating the Amazon's pre-Columbian settlements are using high-tech tools such as satellite imaging and ground-penetrating radar.

Excavating ancient ruins is still important, but it's now being aided by space-age tools.

And the trend isn't limited to the Amazon. Growing numbers of archeologists around the world are using satellite imagery, according to Sarah Parcak, a professor of archaeology at the University of Alabama at Birmingham.

Multispectral satellites, which can provide images in a range of light including infrared, were first launched in 1972. Parcak said her fellow archaeologists are realizing just how useful the devices may be for their research.

"They give us this ability to see beyond what we normally see," Parcak said, adding that she has discovered hundreds of ancient sites in Egypt using satellite images. "They allow you to differentiate between ancient and modern pretty easily."

During Grann's trip into the Amazon to find Fawcett, he met with an American archeologist named Michael Heckenberger, who had been living for years with an aboriginal tribe near to where the British explorer disappeared in 1925.

Heckenberger has used satellite images to help identify nearly two-dozen ancient settlements in the southern Amazon. He believes the tribe he was staying with is made up of their descendants.

Time will tell whether the movie adaptation of Fawcett's Amazonian quests will touch on the ancient societies that eluded the explorer, and are now being discovered.

But a world away from Hollywood, archaeologists appear to be on the cusp of rewriting the Americas' ancient history.