THE BEGINNINGS of the Zen era are about the middle of the twelfth century, when the centuries-long Heian miracle of peace came to an end. The Japanese aristocracy had ruled the land for hundreds of years practically without drawing a sword, using diplomatic suasion so skillful that Heian was probably the only capital city in the medieval world entirely without fortifications. This had been possible partly because of the ruling class's willingness to let taxable lands slip from their control--into the hands of powerful provincial leaders and rich monasteries--rather than start a quarrel. For occasions when force was required, they delegated the responsibility to two powerful military clans, the Taira and the Minamoto, who roamed the land to collect taxes, quell uprisings, and not incidentally to forge allegiances with provincial chieftains. The Taira were in charge of the western and central provinces around Kyoto, while the Minamoto dominated the frontier eastern provinces, in the region one day to hold the warrior capital of Kamakura. The astounding longevity of their rule was a tribute to the aristocrats' skill in playing off these two powerful families against each other, but by the middle of the twelfth century they found themselves at the mercy of their bellicose agents, awakening one day to discover ruffians in the streets of Kyoto as brigands and armed monks invaded the city to burn and pillage. The real downfall of the _ancien regime_ began in the year 1156, when a dispute arose between the reigning emperor and a retired sovereign simultaneously with a disagreement among the aristocracy regarding patronage. Both sides turned to the warriors for support--a formula that proved to be extremely unwise. The result was a feud between the Taira and Minamoto, culminating in a civil war (the Gempei War) that lasted five years, produced bloodshed on a scale previously unknown in Japan, and ended in victory for the Minamoto. A chieftain named Minamoto Yoritomo emerged as head of a unified state and leader of a government whose power to command was beyond question. Since Yoritomo's position had no precedent, he invented for himself the title of shogun. He also moved the government from Kyoto to his military headquarters at Kamakura and proceeded to lay the groundwork for what would be almost seven hundred years of unbroken warrior rule.