A high-resolution LiDAR survey of the Mixteca Alta region of Oaxaca has identified a 1,200-year-old defensive network consisting of fortified outposts and a sophisticated 'Signal Fire System'. The structures are perched on strategic ridgelines, allowing for line-of-sight communication between major Zapotec and Mixtec urban centers during a period of regional conflict. Each outpost features a stone-lined pit containing thick layers of ash and carbonized wood, indicative of large-scale fire signals.
Archaeologists also mapped a series of steep defensive terraces and hidden access tunnels that would have allowed small garrisons to hold the summits against larger forces. The discovery of copper-alloy spearheads and obsidian blades within the towers suggests these were active military installations. This finding provides a new perspective on the complex geopolitical landscape and advanced military logistics of pre-Columbian Mesoamerica.