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Deep in the Amazon rainforest in the South American country of Ecuador, an ancient city lay hidden for thousands of years.

But after 25 years of careful research, its secrets are finally being told.

Aerial surveys have revealed a large network of roads and canals connecting lots of different settlements near a volcano in Ecuador.

The discovery has challenged the idea that ancient civilisations in this area were mainly nomadic - meaning that they often moved around and rarely stayed in one place for long periods of time.

"This is older than any other site we know in the Amazon," says Prof Stephen Rostain who led the research.

The city was mapped out using planes carrying laser sensors. The sensors could analyse the city's remains through the forest that covered it.

Archaeologists also carried out surveys on the ground, and came across evidence of previous civilisations including fire pits, jars and burnt seeds.

The city is thought to have been built around 2,500 years ago and is thought to have been home to tens of thousands of people, if not more.

It means that there is a society that existed that could have been bigger than other well-known South American civilizations like the Mayans.

Researchers also think the city could have been inhabited for up to 1,000 years.

While we do not know a lot about the people who lived in this city and what their lives were like, it reveals how advanced their community was.

"It changes the way we see Amazonian cultures," says co-author of the research, Antoine Dorison.

"Most people picture small groups, probably naked, living in huts and clearing land - this shows ancient people lived in complicated urban societies,".