The Slavs colonized the Balkans during the 4th-7th centuries. They found here two large tribal groups which were in close relationship with one another: to the north, in the lands of today's Romania, lived the Dacians, and to the south of the Danube - the Thracians. Both the Dacians and the Thracians had already been romanized and spoke a Vulgar Latin tongue.

The Dacians inhabiting the lands north of the Danube gradually assimilated the less numerous Slavs and this was how the Romanian people was formed. South of the great river it was the other way about - the native Thracians were absorbed by the Slavonic element, the major "component" of the Bulgarian ethnos.

In the Middle Ages, the Thracians who had not been assimilated by the Slavs came to be known as Wallachians /Vlachs/. They lived in clans, scattered in the high mountains of the Peninsula. More compact groups of them stayed in the region of the Greek mountain of Pindus. Later it was from this particular place that they began to "disperse" to all the other Balkan countries.

Some of the Wallachians, who are probably descendants of Hellenized Thracians, are called Karakachans, They still use in their dialect many Greek words. Only the people known as Kutzowallachs /Kutzovlachs/ have kept their Roman language. It is assumed that the Karakachans number about several thousand persons, and the Kutzowallachs - even less. The majority of them are Eastern Orthodox Christians.

The Karakachans and Kutzowallachs maintained their original culture in the course of centuries owing to their nomadic life in the past. Until the beginning of this century these shepherds spent the period of time between Gherghiovden - St. George's Day (23 April),  and Krastovden - the Day of the Cross (14 September), in the Balkan, Rila, Pirin, and the Rhodope Mountains, then setting off south to winter near the Aegean Sea. These "migrations" were undertaken together with their families, wives and all children, in groups of 50-100 people. These communities consisted of both poor and rich, both masters and servants. They used to raise numerous flocks of sheep and were very good masters in producing various kinds of white and yellow cheese (kashkaval). In addition, each family had a dozen or so of horses.

The free movement of Karakachans and Kutzowallachs was seriously hampered in the first decades of the 20th century, when their century-old routes were confronted with the borders and custom-houses of the Balkan countries. After World War II their migrations ceased altogether. In the Bulgarian lands these "vagrants" were forced to settle in the towns or villages. With very rare exceptions, most of them abandoned shepherdship.

In recent times, Karakachans, supported officially by the Greek Government, have shown a growing interest in their original identity. One can see and learn a lot about their ancient customs, songs, dances, costumes at their traditional summer fair taking place near the town of Sliven, south-eastern Bulgaria.

Along with Karakachans and Kutzowallachs, there are several dozens of thousands "pure" Wallachians living in this country. They are peasants, who, from the 18th century on, kept fleeing to the Ottoman Empire, because taxes and levies there were lower than in their native land, Romania. Wallachians have formed more compact groups in the towns and villages along the southern bank of the Danube, mostly in the vicinity of the town of Vidin.