Defensive networks provide basis for late pre-Hispanic Andean polities.

Defensive networks of pukaras shaped late pre-Hispanic Andean polities, with 1,287 hillforts revealing diverse regional structures from 1250 to 1500 CE.

• Why it matters: Understanding how social and political systems emerged in the Andes helps clarify the role of landscape and conflict in societal development, filling a gap in regional archaeological knowledge.
• What they did: Researchers used formal spatial and network analyses on satellite data to examine intervisibility and walking costs between hillforts, identifying community groupings across the landscape.
• The result: Findings show that open terrain supported larger, less cohesive networks, while rugged areas fostered smaller, more cohesive groups, illuminating how landscape influenced social organization and defense strategies.