The Venetian city state grew during the decline of the Roman Empire as people fled barbarian invasions to the safety of islands in the Venetian Lagoon. Small communities grew in the lagoon, and Venice became the most prominent. The city of Venice became a highly successful trading port, and by the 11th century dominated trade between Europe, North Africa, and the Middle East. It also had a strong navy. Many European Crusaders passed through Venice on their way to and from the Holy Land. Treasures of many kinds were bought and sold in Venice: spices, precious metals, gemstones, ivory, silks—and glass. Successful trade bred a wealthy merchant class in addition to the nobles, and the wealthy became patrons of Venice's famous art and architecture.