In the 9th century, once Byzantium and Bulgaria were on more harmonious terms, trade started to expand and coinage to circulate more freely. Peaceful conditions and settlement of the borders after the 10th century contributed to the opening of new markets (Chazars, Russ).
The activities of commerce and craft industries were co-ordinated by specially constituted professional guilds. Bulgarian products (honey, flax, linen cloth) were imported through Constantinople, while Thessalonike became an important centre of Balkan transit trade (e.g. the Demetria trade fair), which was at its height in the 12th century. Monasteries set up on their lands craft industries producing trade goods; at the same time they enjoyed tax privileges (e.g. the monastery of the Great Lavra).
In the 11th century foreign trade began slowly to pass under the control of western cities (Venice, Pisa, Genoa) which were granted privileges by the emperors. Incursions, famine and the abandonment of the imperial policy, which opposed the growth of large landholdings at the expense of the freemen, who were small cultivators, led to a flight from the land. The increasing needs of the state for money (mercenary troops, gifts and bounties to secure non-aggression) in conjunction with poor management resulted in the progressive devaluation of the currency.