Out of the walls, in the rocky hills, a large number of burials have been carved. Their dimensions vary depending on the arcosols that have been formed inside them, while, individual arcosols also exist. They are dated in the Early Christian period. However, they are not unlikely to belong to an earlier era – at least some of them – until the first Christian era.

The historical testimonies of Thisvi during Byzantium are inadequate and do not substantiate its particular characteristics and the way in which its society is organized. Its ancient name was in use until the Early Christian period. At the end of the Late Byzantine period and during the Ottoman times it reappears under the name “Kakosi”, until 1915, when the settlement was renamed to Thisvi. However, the unbroken habitation of the area during the Middle and Late Byzantine period is revealed by the archaeological superficial, mainly, research carried out at Thisvi. From the middle of the 19th century, the ongoing study and the re-association connects Thisvi with the place-name “Kastorio”, which refers to the life of Saint Loukas (10th century). The identification of Byzantine Thisvi with Kastorio is mainly due to a tax record of 1466/1467. Here is a second name for the village of Kakossi, also called “Kastoria”. Kastorio is no doubt considered to be the birthplace of Saint Lοuκas, the founder of the homonymous monastery of Viotia. His biography describes the escape of his ancestors from Aegina island (in the middle of the 9th century, for the fear of the pirates) to the port of Vathy, as it is today called Thisvi’s seaport. The adjacent mountain, Saint John or Agiannis, is also identified with the place where the Saint led his ascetism   and is called in its biography as “Ioannitzi” or “Jannitzi”.

Commercial and economic importance of Thisvi

Significant for the trade that took place in the natural harbors of Thisvi is the existence of organized residential complexes in the coastal rocky islands, such as Kouveli and Makronisos. The communication of its harbors with the coasts of the Peloponnese and the fact that the access to Central Greece was much shorter through Thisvi contributed to the commercial importance of the city. Through Thisvi the travelers between East and West avoided the tour of Attica and the Peloponnese. The harbors of Thisvi and Agios Ioannis in the early of 20th century were still active as in 1912 there was a customs office there and a small village of 62 inhabitants in 1934. The customs served corn transportation from Kopaida (Central Greece) to the opposite coasts of Peloponnese.