The author examines changing patterns in the decoration set and metal elements of costume traceable by materials offered by the Old Mari burial grounds in the Lower Vetluga area and the neighboring Volga area starting from the middle 11^th century. This process reflects trade and cultural contacts of the Lower Vetluga population in the middle of 11^th – 13^th centuries. The analysis of grave goods from a number of medieval Mari burial grounds in the Lower Vetluga, such as Vyzhum II, Vyzhum III, Dubovo, Rutka, Pochinok, Rusenikha, allowed distinguishing some artefacts originating from the territory of the Old Rus’ and more remote western territories: Finland, Scandinavia, the Baltic Sea zone. The dating and the analogies support the Old Russian origin of the majority of these artefacts. The study allowed linking some types of decoration to certain territories and tribes of the Northern Rus’ and identify their main production centers.