With the xenophobia and intellectual introspection characteristic of the increasingly popular new school of neo-Confucianism, China under the later Ming Dynasty became isolated, prohibiting the construction of ocean going sea vessels. Despite isolationist policies the Ming Economy still suffered from an inflation due to an overabundance of Spanish New World silver entering its economy through new European colonies such as Macau. Ming China was further strained by victorious but costly wars to protect Korea from Japanese Invasion. The European trade depression of the 1620s also hurt the Chinese economy, which sunk to the point where all of China's trading partners cut ties with them: Philip IV restricted shipments of exports from Acapulco, the Japanese cut off all trade with Macau, and the Dutch severed connections between Gao and Macau.