The article deals with how the kinship system operated in practical and ideological terms before the Mongols abolished the traditional clan. The exogamic rule was common, but its application differed among various Mongolian ethnic groups. The exogamic unit was defined essentially, though not exclusively, as agnatic and the number of generations included in the exogamic unit was also an element of variability. The Buriat examples show two forms of separation: the innner separation of the clan, viz. the lineage of a son making separate stock but continuing to belong to the same exogamic unit as the original clan, and the so called formal scission, yielding two different exogamic units, viz. two distinct clans.
Within the Khalkha Mongols, they are considered members of the same exogamous unit with which marriage is forbidden as long as a common male ancestor can be traced back. If in case of commoners the limit of the exogamous unit could be set at three or four generations (among them, exogamy was not strictly observed), but for the Borzigid imperial clan (the Mongolian aristocracy) whose genealogies are updated, the limits were endlessly postponed. Within the Ordos Mongols the clan lost its social reference value in the Manchu time, viz. the individual was no longer named after his clan, but after the banner or the place name or even a nickname. The Dagurs have preserved strong clan traditions unlike the Khalkhas, where only Borzigid really preserved an exogamous, social and political function. Within the Dörvöd one should not find common ancestors in both paternal lineages over a specified number of generations.
The Mongolian language itself testifies respect for the exogamic rule. Mongols do distinguish between paternal links, conceptualised as “bone”, formed by the father’s semen, and maternal links seen as “blood” or “flesh” contributed by the mother. The “bone” filiation is opposed to blood relative which designates the matrilineal kinship. The clans preserved their purity of bonds excluding all individuals whose origin was doubtful. The concept of “alien” was perceived as alien to the patrilineal clan. Within certain Mongolian groups, the clan’s names have survived as well as their role of exogamous delimitation (Buriat and Oirat groups, Darhad as well). The problem is how to observe the exogamic rule when the clan is unknown. The author answers in her conclusion that in absence of clans, the exogamic unit where marriage is prohibited regroups patrilineal kinship over three, four generations. The principles of lineal exogamy are still observed in marriage within the Mongolian ethnic groups, but the evolution of the clan has changed the forms of kinship and its place in society.