This article addresses the question of how vast societies were created by increased interaction among smaller communities through judicial cooperation. This process is explored through two case studies of the law provinces of (1) Gulathing and (2) Hålogaland, Norway, covering a time span of nearly a millennium, from the 3^rd to 13^th century. Central to the discussion of the early phase, during the 3^rd–10^th centuries, are the courtyard sites of Åse and Bjarkøy, Hålogaland, providing key materials to these developments in a northern European context. This material is supplemented by a case study of the Gulathing law area, which is one of only a few Scandinavian cases where the development can be more securely traced from the 11^th to the 13^th centuries. In addition, population size and the number of delegates present at the representative thing are considered.