According to The Institute for Research on World-Systems, Kamakura was the 4th largest city in the world in 1250 AD, with 200,000 people, and Japan's largest, eclipsing Kyoto by 1200 AD. Yet, despite Kamakura's annihilation of Kyoto-based political and military power at the Battle of Dan-no-ura in 1185, and the failure of the Emperor to free himself from Kamakura's control during the Jōkyū War, Takahashi (2005) has questioned whether Kamakura's nationwide political hegemony actually existed. Takahashi claims that if Kamakura ruled the Kantō, not only was the Emperor in fact still the ruler of Kansai, but during this period the city was in many ways politically and administratively still under the ancient capital of Kyoto. Kamakura was simply a rival center of political, economic and cultural power in a country that had Kyoto as its capital.