Cities buried beneath the jungle ground — it sounds like something out of an Indiana Jones film.

Yet Australian archaeologist Damian Evans has spent the past several years searching for them in the dense jungleland near Angkor Wat in Cambodia. During a phone interview early Monday morning, Evans told The Washington Post he and his team have mapped out more than 1180 square kilometres of land, including “basically every modern temple complex in the entire country to some degree.”

The findings offer new insight not only into the Khmer Empire, which reigned in what is now called Cambodia from around the 9th to the 15th centuries, but into the populations that lived in the area long before then.