The article is dedicated to the results of many-years’ (1990–2010) excavations on the ancient Mordovian Steksovo II burial ground site. The burial ground had functioned in the 3^rd to 13^th centuries AD. The investigations revealed hundreds of burials, which enabled the researchers to judge upon the wealth of material items found and the variety of burial rites of the population that had formed the burial ground. The 1^st millennium AD is characterized by bi-ritualism, while inhumation is characteristic of the 11–13^th-century period; horses’ burials were also discovered. The data of the burial ground make it possible to modify the concept of the stages in ancient Mordovians ethnogenesis. It is generally attributed to the Erzya Mordvins, but in early burials the combination of the Erzya and Moksha ancientries is traced. Complexes of the items of crucial importance for the chronology of the burial are discussed in the article with a representation of statistical data characterizing funeral rites and traditions.