Japan's medieval era was characterized by the emergence of a ruling class of warriors called samurai. In the year 1185, general Minamoto Yoritomo was the first to break the tradition of ruling alongside the Emperor in Kyoto, holding power in Kamakura, just south of present-day Yokohama. After Yoritomo's death, another warrior clan, the Hojo, came to rule as regents for the shoguns. The shogunate managed to repel a Mongol invasion from Mongol-occupied China in 1274 and 1281. While this Kamakura shogunate was somewhat stable, Japan soon fell into warring factions and suffered through what became known as the Warring States or Sengoku period.


During the 16th century, traders and missionaries from Europe reached Japan for the first time, initiating the "Nanban" ("Southern barbarian") period of active commercial and cultural exchange between Japan and the West. Around the same time, Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu, established increasingly strong control over the warring states of Japan. Nobunaga's barbaric and authoritarian handling of the country made him an unpopular warlord, though his military genius was not to be ignored. Hideyoshi's disastrous invasion of Korea in 1592 also gave him a bad name in Japanese History, especially after the Japanese were repulsed by the Ming Dynasty Chinese forces and Korean naval forces.


Tokugawa finally reunified the country by defeating his enemies at the Battle of Sekigahara in 1600, moving the capital to Edo (now Tokyo) and starting the Tokugawa shogunate.


The Tokugawa shogunate, suspicious of the influence of Catholic missionaries, barred all relations with Europeans except for severely restricted contacts with Dutch merchants at the artificial island of Dejima. They also became more conscious of trade with China, especially after the Manchu conquered China and established the Manchu Qing Dynasty. The Manchus conquered Korea in 1637, and the Japanese feared a Manchu invasion of Japan. Thus, the country became more isolated than ever before. This period of isolation lasted for two and a half centuries, a time of tenuous political unity known as the Edo period, considered to be the height of Japan's medieval culture.