Seeing through the trees
The Kumano Kodo is a network of ancient pilgrimage trails crossing the dense forests of Japan's Kii Peninsula. For centuries, people from all levels of society have walked these paths to reach the three grand shrines of Kumano: Kumano Hongu Taisha, Kumano Hayatama Taisha, and Kumano Nachi Taisha. While the main routes are well-known and form part of a UNESCO World Heritage site, the thick forest canopy has long hidden the full extent of this medieval network. Traditional ground surveys are slow and difficult in the steep, rugged terrain.
To overcome this, researchers from the Wakayama Prefectural Board of Education's Center for Cultural Heritage used airborne LiDAR (Light Detection and Ranging). This remote-sensing method involves an aircraft firing millions of laser pulses toward the ground. By measuring the time it takes for these pulses to return, a precise and detailed 3D model of the ground surface can be created. The technology effectively filters out vegetation, showing subtle features on the forest floor that are invisible to the naked eye. This digital deforestation allows archaeologists to map vast, inaccessible areas with incredible accuracy.
A lost area found
The LiDAR survey produced a startling discovery: approximately 40 kilometers of previously undocumented stone-paved paths, primarily along the Iseji route. This route connects the Ise Grand Shrine with the Kumano Sanzan and was heavily used during Japan's Edo period (1603-1868). The stone pavements, known as ishidatami, were engineered to protect the steep mountain trails from erosion caused by the region's heavy rainfall.
The high-resolution digital models revealed roads and other features. Archaeologists identified the faint, circular depressions of over 2,300 charcoal kiln sites. These kilns were part of a significant local industry, producing high-quality binchōtan charcoal. The data also showed the foundations of former buildings, likely teahouses and inns that once served the thousands of pilgrims who walked these routes. The discovery of these industrial and commercial sites shows a more complete record of the area's economic life, which supported the pilgrimage for centuries. Many of these paths and structures were simply abandoned as modern transportation routes were built, allowing the forest to reclaim them until this survey.