What is the Historical Meaning behind the title "When China Ruled the Seas: The Treasure Fleet of the Dragon Throne, 1405-1433)

At the time, China's fleet of ships spoke to its naval power, possibly the most powerful naval power of the time. The fleet was involved in extensive exploration and allowed for widespread conquest. It also carried the Emperor's finest porcelains, lacquerware, and silk..... hence..... the treasure.