A new study challenges longstanding assumptions about human habitation in the interior landscapes of prehistoric Iberia during the Ice Age.

Led by Francisco Javier Aragoncillo and published in the journal Antiquity, the research provides fresh evidence that hunter-gatherer groups occupied high-altitude regions of the Iberian Peninsula during the Late Pleistocene, despite what were previously thought to be prohibitive environmental conditions.

Archaeologists long believed that the interior of the Iberian Peninsula -- especially the plateaus and mountainous zones of the central Iberian system -- was largely uninhabited during the early and middle Upper Palaeolithic, roughly 45,000 to 20,000 years ago.

The prevailing explanation was that the region's cold continental climate, high altitude, and limited natural shelter made it too harsh for human survival. Areas along the Tajo-Ebro interfluve, averaging 1,200 meters above sea level and facing long winters below freezing, had yielded almost no confirmed Palaeolithic occupation sites.

Aragoncillo's team set out to determine whether the lack of findings reflected a real absence or simply a gap in research. Through systematic surveys and selective excavations, the researchers explored several upland locations -- Cueva Grande, El Bosque, Ciño Negro, and La Vega de Albarcaz -- in the Castilian branch of the Iberian System. These were places once considered too inhospitable for early humans.

At Cueva Grande, near the headwaters of the Arandilla River at 1,250 meters elevation, excavations revealed flint tools, animal bones, and charcoal fragments. Radiocarbon tests placed the remains in the late Magdalenian period, showing human activity where none had been expected.

At El Bosque, material evidence suggested a brief occupation between the Upper Palaeolithic and early Neolithic.

At Ciño Negro, a burned area and a distinctive burin tool indicated a final Upper Palaeolithic or early Holocene presence.

At La Vega de Albarcaz, a collection of flint and quartzite tools -- some displaying Middle Palaeolithic features -- hinted that humans may have reached the site even earlier than thought.

The discoveries reveal that inland uplands were not barren frontiers. Despite freezing winters and steep terrain, human groups returned repeatedly to these landscapes over thousands of years.

The study suggests that earlier models underestimated how adaptable prehistoric populations were, and that the apparent lack of occupation was likely due to erosion, sediment cover, and limited research rather than true absence.

Aragoncillo's findings add to growing evidence that humans inhabited central Iberia even during the harshest phases of the last Ice Age. Recent studies in other parts of the Iberian Meseta also show traces of Upper Palaeolithic and early Holocene life, overturning the old idea that the region was a "no man's land."

The researchers emphasize that their work is preliminary, but it opens a new chapter in the study of Iberian prehistory. The uplands, once dismissed as uninhabitable, now appear to hold key clues about human resilience and adaptation.

In the end, the study reshapes how scientists view prehistoric Iberia -- less as an empty, frozen plateau and more as a landscape that challenged, but never entirely deterred, early human life.