A modern map makes Iceland, Greenland and Norway look like points connected by a line.

Medieval sailors experienced something very different.

Voyages depended on wind, visibility, sea ice, ship condition, navigation knowledge and the ability to carry enough provisions.

A trip that failed could cost a vessel and its crew.

If the number of ships declined, the entire Greenland economy would feel the effect.

Isolation was therefore not a permanent condition; it could intensify dramatically when maritime traffic weakened.

This helps explain why imported iron mattered so much.