A new high-tech study has revealed nearly 1,000 ancient Maya settlements, including 417 previously unknown cites linked by what may be the world’s first highway network and hidden for millennia by the dense jungles of northern Guatemala and southern Mexico.

It is the latest discovery of roughly 3,000-year-old Maya centers and related infrastructure, according to a statement on Monday from a team from Guatemala’s FARES anthropological research foundation overseeing the so-called LiDAR studies.

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The findings were first published last month in the journal Ancient Mesoamerica.

All of the newly-identified structures were built centuries before the largest Maya city-states emerged, ushering in major human achievements in math and writing.

Read more: Reuters