All Norse lands outside Norway that paid 'skatt' (i.e. tax or tribute) to the King of Norway and thereby accepted him as the rightful lord of the land were labelled 'skattland' in the Middle Ages. While 'skatt' occurs in all Scandinavian languages, the term 'skattland' is documented in Norwegian only. However, the actual phenomenon of tribute-paying dominions is also well known in the kingdoms of Sweden and Denmark. Thus Gotland and Rügen like Man and the Isles were forced to pay tribute to their overlords in Sweden, Denmark and Norway respectively. In other words, 'skatt' and 'skattland' are indissolubly tied to the formation of realms and states and the relationship between the mainland and dependencies. This book will focus on the phenomenon 'skatt' in general and 'skattland' as part of different Nordic realm-formation projects in the Viking and Middle Ages. 'Norden' here is to be understood as the part of Northern Europe that between c.800 AD and c.1600 became subject to Scandinavian political domination. This book is the second in a series of four planned volumes on the Norwegian realm and its dependencies in the Central Middle Ages.