In 1185, Japan's Taira (Heike) and Minamoto (Genpei) clans played out the final battle of the Genpei War, the result of which would have a profound effect on Japan ushering in its first shogun with Kamakura as the shogunate.

In the latter part of the 12th century, the entire archipelago was in turmoil as the two clans asserted their power. The era saw violent rebellions by monks and the conflagrations of Todaiji and Kokufuji temples in Nara, two of Japan's most important places of worship. War and famine spread. So dark and tumultuous were these times, that many Japanese people feared they had entered "mappo" — the end of the Buddhist Dharma, or the age of degeneration.

The final stand-off in the Genpei War took place in the Shimonoseki Strait between Honshu and Kyushu at Dannoura where the Seto Inland Sea spills out through the narrow channel into the Japan Sea.