Great Vlachia or Great Wallachia (; ), also simply known as Vlachia (; ), was a province and region in southeastern Thessaly in the late 12th century, and was used to denote the entire region of Thessaly in the 13th and 14th centuries. The name derives from the Vlachs (Aromanians), who had lived across much of the area. Name The name derives from the Aromanians or Vlachs, a chiefly transhumant ethnic group that lives in several mountainous areas of the Balkans, descended from ancient Romance-speaking populations mixed with the people from the Barbarian Invasions of Late Antiquity. In the broadest sense, both Greek and Western sources of the later Middle Ages—like the French, Italian, and Aragonese versions of the Chronicle of the Morea, or the chroniclers Ramon Muntaner and Marino Sanudo Torsello—used "Vlachia" or similar names (Blaquie, Blaquia, Val[l]achia) to refer to all of Thessaly, from the Pindus mountains in the west to the Aegean Sea in the east, and from the area of Mount Olympus and Servia in the north to the towns of Zetouni (Lamia) and Neopatras (Ypati) in the south. Thessalian Vlachia was apparently also known as "Vlachia in Hellas" (), as well as "Great Vlachia" (Μεγάλη Βλαχία), to distinguish it from other Vlach-inhabited areas, "Upper Vlachia" in Epirus, and a "Little Vlachia" in Aetolia-Acarnania. The contemporary Byzantine historian Niketas Choniates however distinguishes "Great Vlachia" as a district near Meteora. "Vlachia", "Great Vlachia", and the other variants began to fall out of use for Thessaly at the turn of the 14th century, and with the emergence of Wallachia north of the Danube, from the 15th century the name was reserved for it. Thessalian Vlachs in the Middle Ages The Vlachs of Thessaly first appear in Byzantine sources in the 10-11th century,like in the Strategikon of Kekaumenos and Anna Komnene's Alexiad. Kekaumenos, who wrote in the late 1070s, in particular stresses both their transhumance as well as their disdain of imperial authorities. Kekaumenos records a failed Vlach uprising of 1066, under the unwilling leadership of Nikoulitzas Delphinas, a relative of his and grandson of the original Nikoulitzas, whom Emperor Basil II (r. 976–1025) placed to rule over the Thessalian Vlachs. Anna Komnene reports a Vlach settlement near Mount Ossa in 1083, in connection with the campaign of her father, Alexios I Komnenos (r. 1081–1118), against the Normans. In the 12th century, the Jewish traveller Benjamin of Tudela, who