The Severians are believed to have continued the East Slavic tribal union along the middle Dnieper valley, after the political disappearance of the
Antae and
Dulebes, either independently or under Khazar policy. It is presumed they inhabited the lower
Desna and upper
Sejm and
Sula rivers. They were thought to have been centered in
Chernihiv ("black city" However, as the Severians in the historical sources inhabited both the Dnieper valley and a part of the
Danube valley, and as the
Zeriuani realm was said to be so great that all Slavs traced their origins to it,
Henryk Łowmiański believed that the
Ruthenian Severians were the Slavic mother tribe. Some Severians settled in the territory of present-day northeastern
Bulgaria, (
Moesia Inferior, and
Scythia Minor). According to
Theophanes the Confessor, the
Bulgars subjugated the so-called
Seven Slavic tribes. One of these tribes, the
Severeis, were resettled in the east "from the
klisuras before Veregava" (), most likely the
Rish Pass of the
Balkan Mountains; while the other six tribes were resettled in the southern and western regions, as far the boundary with the
Pannonian Avars. In 767, the
Byzantines kidnapped the Severian
prince Slavun, who had made trouble in
Thrace, indicating they retained a tributary relationship with the Bulgars. Those tribes had to pay tribute to the
Khazars in 859 in the form of
squirrel and
beaver skins, which suggests they lived in or near the northern forests. In 884,
Oleg of Novgorod annexed their territory to the
Kievan Rus'. The Severians had to pay a "light tribute." According to Oleg, he had acted not against the Severians but against the Khazars. It is possible that the Severians accepted Oleg's rule because he imposed lower taxes on them. In the 10th century, in his
De Administrando Imperio,
Constantine VII wrote that in winter, the Rus princes (
archontes) moved to and were maintained in the lands of their Severian and Krivich tributaries. Scholars disagree about the abovementioned dates. Some place Oleg's conquest in the 920–930s; the Khazar ruler Joseph (c. 955) mentioned that his empire ruled over the "
Sever,
Slaviun, and
Ventit"; while Constantine VII wrote that the Severians paid tribute to the Rus and not the Khazars c. 950. and gave their name to the region of
Severia. ==Culture==