Secret pyramids and small cities dating back to the Middle Ages have been discovered in one of the densest parts of the Amazon.

According to a journal published in Nature, a new type of advanced laser-mapping technology was used to penetrate the dense Bolivian rainforest of the region.

By deploying this new research tool, archaeologists have now made the landmark discovery of town-like civilisations in the area.

The discovery is particularly exciting for researchers as this now proves that Amazonians lived together in township-like structures before the Spanish set foot on South American soil.

Colorado State University archaeologist Chris Fisher said the new technology will usher in a new age of research in the Amazon, as per The Wall Street Journal.

“This is the first of what I hope will be a huge series of studies that will blow the lid off of preconceptions about what pre-Hispanic polities looked like in the Amazon in terms of their complexity, size and density,” he said.

Dr Fisher said that before Hispanic occupation in the 16th century it was believed Amazonians lived in small groups with limited social development and agricultural systems.

However, this landmark discovery indicates that may not have been the case.

Dr Fisher added: “These sites are pushing the boundaries of what we would call cities.”

Scientists from Germany and the UK searched six regions of the Amazon in Bolivia using a helicopter equipped with light detection and ranging equipment.

The new type of research has paid them back in spades, with 26 settlements revealed to them in unprecedented new detail.