What role did constantinople play in medieval europe’s economy until the 12th century?

The correct answer to this open question is the following.

The role that Constantinople played in medieval Europe’s economy until the 12th century was of the main hub or center for trade.

In that time, Constantinople, the capital of the Byzantine Empire, was the most important city in the region. Many merchants for all over Europe, Asia, and North Africa, and even India gathered in Constantinople to trade their goods. Constantinople was a modern metropolis for that time that had beautiful architecture and modern services to host such a diverse combination of ethnicities