Vlachs in Bosnia and Herzegovina are a Balkan population who descend from Romanized Illyrians (Illyro-Romans), Thracians (Thraco-Romans) and other pre-Slavic Romance-speaking peoples and the South Slavs. They practiced transhumance as herdsmen, shepherds, farmers, and in time developed peculiar socio-political organizational units known as katuns. They traded livestock products. Vlach cheese was reputable because of its fat content and fetched high prices. With their caravans, Vlach carried out much of the traffic between inland and coastal cities such as Dubrovnik. Marko Vego argued that Vlach autochthony with Vlach settlements named after Vlach tribes, Vojnići and Hardomilje, are found near Roman forts and monuments. Bogumil Hrabak supported Vego's assertion that the Vlachs preceded both Turks and Bosnian Slavs in Zachlumia. Dominik Mandić argued that some Vlachs from Herzegovina migrated there from Thessaly, Epirus and Macedonia before the Ottoman invasion into Southern Europe. It is argued that some also arrived from the East during the Ottoman wars. History Vlachs are first mentioned in Bosnian documents in c. 1234 by ban Matej Ninoslav. Sources from 1361, 1385, 1399, 1406, 1407, 1408 and 1417 among others mention them in relation to Bosnian bans and kings Vlachs in the Bosnian state of Tvrtko I were considered as military element. The relationship of Vlach katuns and feudal holdings can be traced from the 14th century. By 1382 they were under the jurisdiction of the Bosnian ruler, to later be assigned to large landowners. The Vlachs and lords relationships indicate that medieval Bosnia was not compact – some Vlach vassals (Gleđević) of the rulers were far from royal lands. Some Vlach vassals (Nenko Krajsalić, Radoslav Borojević) became vassals fairly late although Kosača ruled certain lands near Eastern banks of Neretva river for fifteen years. Some Vlach vassals (Maleš) were partly Pavlović and partly Kosača vassals although working on Kosača holdings. In 1382, Vukoslav Piščić was named as knez of all Vlachs by King Tvrtko I of Bosnia. As the earliest noble landowners, in Herzegovina they were assigned to the Sanković noble family, with katun Tomić. In 1409, when Tvrtko I conquered parts of Rascia and Zeta they were located around 100 katuns. They were mentioned as "Vlachorum congregationes et cetus". In the area around Stolac and Zabljak were so many Vlachs that at the end of the 15th century the territory was as Donji Vlasi (Lower Vlachs). The Gornji Vlasi (Upper Vlachs) were only mentioned by Mavro Orbini.