economic activity. Especially in Thessaly, this process manifested itself in the appearance of at least nine new cities, including Halmyros and Stagoi, and the resettlement of older ones, such as Zetounion (ancient Lamia). Byzantine rule in the 10th–12th centuries During the course of the 10th century, the Saracen threat receded and was practically ended as the result of the Byzantine reconquest of Crete in 960–961. The threat from Bulgaria remained, however, and in 986, during his wars with Basil II (), the Bulgarian tsar Samuel sacked the city of Larissa and occupied Thessaly. The Bulgarian ruler undertook another large-scale expedition through the province and into the Peloponnese in 997, but on his return he suffered a devastating defeat at the Battle of Spercheios. In the early 11th century, Thessaly was separated from Hellas and joined to the theme of Thessalonica. The Spercheios valley however remained part of Hellas, with the new border running along the Othrys–Agrafa line. The region enjoyed a long period of peace at this time, interrupted only by raids during the uprising of Petar Delyan (1040–1041), plundering by the Uzès in 1064, and the brief Norman attack into Thessaly in 1082–1083, which was beaten back by Emperor Alexios I Komnenos (). The Vlachs are first mentioned in Thessaly during the 11th century, in the Strategikon of Kekaumenos and Anna Komnene's Alexiad. In the 12th century, the Jewish traveler Benjamin of Tudela recorded the existence of the district of "Vlachia" near Halmyros, while the Byzantine historian Niketas Choniates placed a "Great Vlachia" near Meteora. The term is also used by the 13th-century scholar George Pachymeres, and it appears as a distinct administrative unit in 1276, when the pinkernes Raoul Komnenos was its governor (kephale). Thessalian Vlachia was apparently also known as "Vlachia in Hellas". In the aftermath of the failed Norman invasion, Alexios I granted the first trading privileges to the Republic of Venice, including immunity from taxation and the right to establish trade colonies in certain towns; in Thessaly, this was Demetrias. These concessions signalled the beginning of the ascendancy of the Italian maritime republics in maritime commerce and their gradual takeover of the Byzantine economy. Alexios' successors tried to curb these privileges with mixed success, but in 1198 Alexios III Angelos () was forced to concede even more extensive ones, allowing the Venetians to create trade stations at Vlachia, the "two Halmyroi", Grebenikon, Pharsalus, Domokos, Vesaina,