Treasure of the Land of Darkness traces the traffic in fur from the lands of the north, through the major trade centres of medieval Russia to the consumer markets of the world, stretching from western Europe to China. Professor Martin reconstructs the fur-trade network of each centre (including Kiev, Novgorod and Moscow) and examines the changes they experienced. She shows how aggressive principalities enhanced their political authority through manipulation of such factors as fur resources and trade routes: thus the mid-sixteenth-century supremacy of Muscovy was based upon both political advantage and monopolisation of the networks of the fur trade. Quantitative analysis of the available data substantiates this conclusion: control over the trade of those 'lands of darkness' mentioned in contemporary Islamic texts was of fundamental importance to the political development of medieval Russia.