Why were travel and communication difficult in medieval Greece?

Travel and communication in medieval Greece were primarily hindered by the region's challenging geophysical structure. The southern Balkan Peninsula lacks a central geographic focal point, and its landscape is highly fragmented by mountain ranges, such as the Pindus and Rhodope Mountains, which rendered many interior areas largely inaccessible.1

Furthermore, the major administrative centers of the era, such as Thessalonica and Constantinople, were situated on the periphery of the peninsula rather than within its rugged interior. This geographic isolation meant that state authority often remained a distant influence in the lives of inhabitants living in mountainous regions. While the sea provided a vital means of communication and trade, it also exposed the region to constant threats of invasion and dislocation from various directions, further complicating stable travel and regional connectivity throughout the Middle Ages.1