When Tokyo was but a fishing village and Kyoto a mountain hamlet, big things were happening in Osaka. The Osaka-Nara region was the center of the emerging Japanese (Yamato) nation into the ninth century, and in 645 Emperor Kotoku (596-654) made Osaka his capital. He called it Naniwa, but the city's imperial ascendancy was brief. Until the 8th century capital cities were relocated upon an emperor's death. As a result, Osaka was the royal seat for a fleeting nine years. Despite changes in its political fortunes, Osaka developed as a trade center, a role its waterways had destined it to play. Exchange wasn't limited to commerce. Buddhism and Chinese characters filtered into the fledgling Japanese society through Osaka to Nara, and from Nara to the rest of the country. By 1590 Toyotomi Hideyoshi (1536-98), the first daimyo (warlord) to unite Japan, had completed construction of Osaka Castle to protect his realm against the unruly clans of Kyoto. He designated Osaka a merchant city to consolidate his position. After Toyotomi died, Tokugawa Ieyasu's (1543-1616) forces defeated the Toyotomi legacy at the Battle of Sekigahara in 1600. Osaka's strategic importance was again short-lived, as Tokugawa moved the capital to Edo (now Tokyo) in 1603. Osaka grew rich supplying the new capital with rice, soy sauce, and sake as Edo transformed its agricultural land into city suburbs. All copper produced in Japan was exported through Osaka, and the National Rice Exchange was headquartered in Dojima, near Kita-shinchi. "70% of the nation's wealth comes from Osaka," was the catchphrase of the era. Some of Japan's business dynasties were founded during the economic boom of the 17th century, and they prevail today—Sumitomo, Konoike, and Mitsui among them. By the end of the Genroku Era (1688-1704) Osaka's barons were patronizing bunraku puppetry and kamigata kabuki (comic kabuki). Chikamatsu Monzaemon (1653-1724), writer of the The Forty-Seven Ronin, penned the tragedies which quickly became classics. Ihara Saikaku (1642-93) immortalized the city's merchants in the risqué Life of an Amorous Man and the The Great Mirror of Male Love. When Tokyo became the official capital of Japan in 1868 there were fears that the "Venice of the East" would suffer. But expansion of the spinning and textile industries assured prosperity, and earned Osaka a new epithet-"Manchester of the East." As a consequence of the Great Kanto Earthquake in 1923, Osaka became Japan's main port and by 1926 the country's largest city. Chemical and heavy industries grew during World War I, and were prime targets for American bombers during World War II. Much of Osaka was flattened, and more than a third of the prefecture's 4.8 million people were left homeless. During the postwar years many Osaka companies moved their headquarters to Tokyo. Even so, Osaka was rebuilt and went on to host Asia's first World Expo in 1970. It has since fashioned itself as a city of cutting-edge techonology and lifestyle. The Osaka City Government plans to revive the "Water City" appellation for Osaka, but for now the heritage of the city's waterways lives on in its place names: bashi (bridge), horie (canal), and semba (dockyard).