Seoul. Seoul is the traditional capital of North Korea, and Pyongyang was built later by North Korea. Later, with the advantages of North Korean socialism, Pyongyang gradually surpassed Seoul. However, after the Seoul Olympics, a large number of multinational companies came to invest in South Korea, and Seoul gradually became more developed than Pyongyang. In 1994, Russia stopped providing low-price crude oil to North Korea, and Pyongyang began to decline.