What state-controlled industry was a major source of Byzantine wealth?

The Byzantine state’s silk monopoly was a major source of imperial wealth. Silk was valuable not only as luxury clothing but also as a means of payment, taxation, diplomacy, and portable wealth.

Raw silk initially reached the empire through long-distance trade with China and Persia. According to Byzantine tradition, silkworm eggs were smuggled into the empire during Justinian I’s reign in the sixth century, allowing production to expand in Constantinople and other centers.

After silk manufacture became established, imperial regulations controlled production, dyes, workshops, prices, and permitted buyers. Particularly costly purple silks were closely associated with the emperor and court. Authorized silk merchants and state-supervised workshops helped the government capture revenue from the industry.

A common mix-up is to identify purple dye itself as the answer. Purple was certainly regulated and politically important, but it was part of the broader silk industry. Byzantine silk also served as a diplomatic tool: richly woven textiles were given to foreign rulers and allies, spreading Constantinople’s influence across Europe and the Mediterranean.