Horizontal bonds were crucial for the formation of elite networks at the top level of society. In contrast to patron-client relationships, horizontal bonds were formed between parties of equal status. They could be sealed through various means, such as marriages, fosterage, pacts, or oaths. Such networks probably furnished the most important vehicle for elite power in medieval Scandinavia, since formalized institutional bonds played a rather limited role in this period – albeit an increasingly important one. Horizontal bonds at the elite level could be of varying reach, from the local to the trans-regnal, implying that medieval elites maneuvered fairly independently of national borders. However, horizontal bonds were not necessarily very stable. The fragility of horizontal bonds emerges from the Icelandic example, contrasting with the stability of patron-client relationships. Yet, in other instances, such as with the Hvide clan/group in Denmark, horizontal bonds could provide the basis for quite stable political alliances. Networks became more formalized and specialized during the High Middle Ages, and they were increasingly squeezed by more formal obligations emanating from Church and monarchy. However, informal social networks continued to play a crucial role for Nordic elites throughout the Middle Ages.