When the Mediterranean was socially networked by the trading ships of Phoenicians, Greeks, Arabs or Venetians, culture and prosperity advanced. When the network collapsed because of pirates at the end of the second millennium B.C., or in the Dark Ages, or in the 16th century under the Barbary and Ottoman corsairs, culture and prosperity stagnated. When Ming China, or Shogun Japan, or Nehru's India, or Albania or North Korea turned inward and cut themselves off from the world, the consequence was relative, even absolute decline.
Knowledge is dispersed and shared. Friedrich Hayek was the first to point out, in his famous 1945 essay "The Uses of Knowledge in Society," that central planning cannot work because it is trying to substitute an individual all-knowing intelligence for a distributed and fragmented system of localized but connected knowledge.