Why did China's naval power decline in the 1500's?

Historians believe China destroyed its magnificent fleet in 1500 because it was afraid of their trade becoming uncontrolled. By the late 19th century, there was also anxiety about trade. Many western countries, and Japan had interest in China. Peking's swelling population of foreigners caused anxiety to residents.

The "I Ho Ch'uan" (Society of "Righteous and Harmonious Fists") (named Boxers) opposed foreign influence and was strongly anti-Christian. Farmers and other workers affected by floods, then droughts joined the Boxers. They began harassing Chinese Christians and foreign missionaries. It culminated in the Battle of Peking. The "Imperial Chinese Navy" refers to the Qing navy and the Qing regime ended in 1912.

China’s naval power didn’t just decline in the 1500’s; it was purposely left to rot and virtually destroyed as a result. In 1403, the Chinese Emperor, Yongle, issued an imperial order to begin construction of a naval fleet. The fleet eventually grew to include many trading ships, warships, and support vessels.

From 1403 to 1433, the fleet made seven voyages to Africa and back, stopping at many Eastern Asian nations, India, and ports along the way bringing back many treasures. It is not clear why the voyages stopped. One reason that has been suggested is that the costs for outfitting the ships was too expensive, especially while Emperor Yongle was fighting a land war with the Mongols.