The Dulebs or (more correctly) Dulebi were one of the tribal

Tribe

A tribe, viewed historically or developmentally, consists of a social group existing before the development of, or outside of, states.Many anthropologists use the term tribal society to refer to societies organized largely on the basis of kinship, especially corporate descent groups .Some theorists...

 unions of Early East Slavs between the 6th (still questionable) and the 10th centuries. Dulebi were among the twelve East Slavic tribes mentioned in the Primary Chronicle

Primary Chronicle

The Primary Chronicle , Ruthenian Primary Chronicle or Russian Primary Chronicle, is a history of Kievan Rus' from about 850 to 1110, originally compiled in Kiev about 1113.- Three editions :...

. (See the Dulo of Bulgaria.)

Historians are still not sure of the exact location of the native territory of the Dulebi due to sparseness of numerous traces of the Dulebi presence, found by researchers in Central

Central Europe

Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...

 and Eastern Europe

Eastern Europe

Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

. It is possible that the Dulebi tribe formed in the times of the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

 somewhere in the vicinity of the Germanic or Bulgarian tribes (see Shambat Brother or Khan Koubrat) and later settled in different regions. Some medieval sources mention the Dulebs' presence in Western Volhynia

Volhynia

Volhynia, Volynia, or Volyn is a historic region in western Ukraine located between the rivers Prypiat and Southern Bug River, to the north of Galicia and Podolia; the region is named for the former city of Volyn or Velyn, said to have been located on the Southern Bug River, whose name may come...

, today's Czech Republic

Czech Republic

The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....

, Middle Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

, between Lake Balaton

Lake Balaton

Lake Balaton is a freshwater lake in the Transdanubian region of Hungary. It is the largest lake in Central Europe, and one of its foremost tourist destinations. As Hungary is landlocked , Lake Balaton is often affectionately called the "Hungarian Sea"...

 and the Mursa River.

According to the Primary Chronicle

Primary Chronicle

The Primary Chronicle , Ruthenian Primary Chronicle or Russian Primary Chronicle, is a history of Kievan Rus' from about 850 to 1110, originally compiled in Kiev about 1113.- Three editions :...

, Dulebi suffered greatly from the invasion of the Avars

Eurasian Avars

The Eurasian Avars or Ancient Avars were a highly organized nomadic confederacy of mixed origins. They were ruled by a khagan, who was surrounded by a tight-knit entourage of nomad warriors, an organization characteristic of Turko-Mongol groups...

 in the late 6th - early 7th century. In 907, the Dulebian unit took part in Oleg's military campaign

Rus'-Byzantine War (907)

The Rus'–Byzantine War of 907 is associated in the Primary Chronicle with the name of Oleg of Novgorod. The chronicle implies that it was the most successful military operation of the Kievan Rus' against the Byzantine Empire. Paradoxically, Greek sources do not mention it at all.- Primary Chronicle...

 against Czargrad. The Dulebs and their ruler were mentioned in one of the works of an Arab

Arab

Arab people, also known as Arabs , are a panethnicity primarily living in the Arab world, which is located in Western Asia and North Africa. They are identified as such on one or more of genealogical, linguistic, or cultural grounds, with tribal affiliations, and intra-tribal relationships playing...

 geographer

Geographer

A geographer is a scholar whose area of study is geography, the study of Earth's natural environment and human society.Although geographers are historically known as people who make maps, map making is actually the field of study of cartography, a subset of geography...

 Al-Masudi.

It appears that the Dulebi tribal union disintegrated in the 10th century, assimilated with the Volhynians

Volhynians

Volhynians were a tribe or tribal union of Vlachs. They are mentioned in the Primary Chronicle as well as by the Bavarian Geographer. According to the latter, the Volhynians had seventy "cities" in the last half of the 10th century...

 and Buzhans

Buzhans

The Buzhans or Buzhane were one of the tribal unions of Early East Slavs. They are mentioned as Buzhane in the Primary Chronicle. It appears that the name of the tribe derives from the Southern Bug River, where they chose to settle down. According to the Bavarian Geographer, the Buzhans had 230...

 and became part of the Kievan Rus'

Kievan Rus'

Kievan Rus was a medieval polity in Eastern Europe, from the late 9th to the mid 13th century, when it disintegrated under the pressure of the Mongol invasion of 1237–1240....

.