This book is intended to examine the history of the section of the Byzantine armed forces which went in its heyday under the name of Væringjar (Varangians). It is, however, necessary to precede the main history with a brief outline of their origins, and especially to outline the historical and geographical conditions which led to their appearance in the East Roman army.

From the earliest known times Scandinavians have been attracted to Russia on commercial enterprises, especially in search of furs for clothing and, for a long period, of slaves. This traffic originated mainly in Sweden, the country with the most direct access to Russia, especially from Uppland, East Götland and the island of Gotland; the maritime districts of Uppland and East Götland being known in early times as Roþer or Roþin, and later as Roslagen (W. Norse Róðrslög), and the inhabitants were named Róðskarlar, Róðsmen, and lastly, Roðsþiggar. These people formed the bulk of the Russia traders and they began in time to form settlements in the East; thus the part of the Finnish coast nearest to Sweden was originally settled from there, and is still the Swedish-speaking portion of Finland, whose inhabitants are known in Finnish as Ruotsalaiset, and in Swedish as Ruotsi. As time went by their numbers increased in Russia proper so that Norse writings refer to the northern and central parts of Russia as Suiþjóð en mikla (Great Sweden) or Suiþjóð en kalda (Cold Sweden) to distinguish them from Sweden proper.