Minamoto Yoritomo established the capital of his new military government in familiar surroundings at his home town of Kamakura, the former small fishing village on the western extent of the Kanto Plain once governed by his great grandfather . Situated in a scenic valley on the northeastern edge of Sagami Bay amid the lush foothills of a craggy mountain range that surrounds the town on three sides, it was both easy to defend and difficult to invade. Where Taira no Kiyomori had only limited military control in the immediate area around the imperial capital at Heian-kyo, Yoritomo's military dominance was nationwide. Kiyomori exercised his authority from behind the scenes and largely through the old civil government structure in the tradition of the Fujiwara before him. Yoritomo declined to dethrone the emperor and created an entirely new and separate governmental structure closely linked with the old civil administration, but independent of it and separately based Kamakura.
The post of shogun was, in theory at least, purely military, so Yoritomo's administration and those of later military rulers came to be known as the shogunate, bakufu, or "tent government," to distinguish it from the civil government in Heian-kyo. As the samurai clans under the Minamoto began building political power, Japan's political center shifted away from Heian-kyo toward the Kamakura bakufu, leaving Heian-kyo as the symbolic, religious and cultural center of Japan. The Kamakura Shogunate set down a pattern of rule in Japan that would last for some seven centuries.
Throughout most of Japanese history, the power of the emperor, tenno, has been either limited or purely symbolic. Still, all Japan's effective rulers, from the Fujiwara and Hojo regents to the Minamoto, Ashikaga and Tokugawa shoguns, respected the emperor and were anxious to secure their legitimacy as rulers of Japan by seeking approval from the imperial throne. China tolerated no ruling authority except that of its emperor. Korean monarchs sought legitimacy by gaining approval from the Chinese emperor. Japanese shoguns sought legitimacy, not from any foreign ruler, but from their own emperor.
Because almost any shogun had the power to interfere with imperial succession, the emperor selected shoguns as political rulers on a regional basis. Since these military men who ruled local populations were not related to the imperial family, their legitimacy depended heavily on the perception they were ruled by the emperor. This form of government rule has been referred to as "centralized feudalism." The Kamakura Shogunate set down the pattern for a new, land-based feudal government that was much simpler than the previously adopted Chinese system and worked much more efficiently for the Japanese.
Yoritomo's real power rested on his personal band of warrior vassals, called "honorable house men," gokenin, which he had built up on the Kanto Plain. After confiscating lands from the defeated Taira clan, he...