When King Kojong was in reign, a large Mongolian army crossed the Yalu River and attacked Koryo (Hatada, 52). Here's an excerpt from Koryo-sa in 1254 describing the attack: "...men and women seized by the Mongol troops reached the enormous number of 206,800, and innumerable people were massacred." (Hatada, 52). These types of events happened repeatedly. These numerous invasions were a clear causes of deteriorating a country.
             Mongolians were not the only ones who attacked Koryo. Koryo had to face the increasing problems of Japanese piracy (Han, 179). These Japanese pirates, also known as Woegu (dwarfs) constantly attacked the coasts of China and Korea. Woegu would sail up river to attack large cities such as Kongju and Chonju (Han 180). Many farmlands of these coastal areas were losing transportation of tax grain to the capital and also losing government food cargo ships (Hatada, 54). The interference of Woegu destroyed many coastal lands and capital goods. This is ano
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