A type of residential structures, which is unique for the Golden Horde period sites, the basement of a merchant’s house, discovered during the excavations of the city of Azaq, is considered in the article. There are only 20 facilities of the kind known in Azaq. They differ from the ordinary semi-subterranean dwellings by their larger space; besides, rare imported and stock-in-trade items have been discovered there. A detailed description of two dwellings with basements, which were investigated in 2002 and 2009-2010, is provided in the article, and their comparative analysis is offered. The results of the analysis have made it possible to define the trade sphere of these merchants’ houses, monitor major directions of trade routes and identify their differences.