In Byzantium, fairs played a significant role in the growth of trade, particularly in provincial towns. Just as today, they were held on the occasion of a religious festival and were accompanied by various events, food, dances and songs. Many traders came and set up a flea market or trade fair offering goods of all kinds. Depending on demand this lasted for a short time, usually over a few days either side of the feast day.

Trade fairs were a source of considerable revenue to the state, since it collected a tax, the kommerkion, equivalent to one tenth of the value of goods. Churches also profited from the money left by the faithful, especially if fairs took place in major pilgrimage centres, such as those of St. Simeon the Stylite in the grounds of the monastery near Aleppo, Saint Demetrios outside the western walls of Thessaloniki, and Saint Eugenios in Trabzon.

Fairs were held in easily accessible places, e.g. near ports or on major roads, in order to facilitate the attendance of traders and visitors as well the transfer of goods. They were set up in a makeshift fashion in open spaces near the church that was celebrating, or even outside the city walls where there was enough available space for merchants to lay out their wares (fabrics, carpets, foodstuffs, leather, animals, etc.), and room for people to move freely between them. In addition to convenience, the positioning of fairs outside the city offered the residents protection, as it kept out strangers who may have been spies or enemies. In the general commotion that prevailed due to the celebration, evil intent could not be ruled out. For example, in 904 Arabs posing as merchants arrived by ship at the port of Demetriada (now Volos); they were allowed to stay, but during the night they took the city by scaling the walls, killing the guards and opening the gates from the inside, to let in others who had arrived by ship in the meantime. Such security reasons led to the adoption of rules concerning the positioning of fairs, as in the case of the Justinian code, which stipulated that fairs involving the citizens of the Byzantine State and the kingdom of Persia could take only take place in peacetime, at set locations.

The aforementioned events do not mean that fairs were dangerous. On the contrary, they were an important part of the social life of the empire’s inhabitants, who greatly enjoyed them. The entertainment included performances by wandering troupes of mimes, skilled acrobats, tightrope walkers and magicians, as well as demonstrations of animals playing or dancing to the sound of drums. Other sources of wonder were people with strange physical attributes or deformities, such as giants and dwarfs, who were put on display in public places and paraded around the streets.

During the fairs, several petty criminals, quacks, astrologers and charlatans had the opportunity to deceive naïve people, by selling them herbs or charms with supposedly miraculous properties. Together with excesses or deviations from proper behaviour as far as entertainment was concerned, this provoked some church writers to criticise fairs. They advised people to be careful not to go to excesses and not to trust miracle workers.