Between the sixth and twelfth centuries, the Yamato kings turned a loose alliance of clans into a state modeled on China, then slowly let that model drift into something distinctly Japanese. Much of the change arrived across the sea from Korea and China: writing, Buddhism, law codes, city planning and ideas of what a ruler should be.

Buddhism arrives

According to Japan's early chronicles, Buddhism reached the court from Baekje, a kingdom in southwestern Korea, in the sixth century. The traditional dates are 538 or 552, depending on the source. The king of Baekje sent an image of the Buddha and scriptures, hoping for military help against his rivals. At court, the powerful Soga clan championed the new faith, while the Mononobe argued that honoring foreign gods would anger the native kami, the spirits of mountains, rivers and ancestors. The Soga won a short war in 587. From then on, Buddhism and kami worship (much later called Shinto) lived side by side, often in the same sacred places.

Shotoku and the Seventeen Articles

Prince Shotoku (574 to 622) served as regent for his aunt, Empress Suiko, the first woman known to have reigned in her own right. He is credited with founding temples such as Horyuji and with sending embassies to Sui China. He is also credited with the Seventeen-Article Constitution of 604, a set of moral rules for court officials rather than a code of laws. It opens, in W. G. Aston's 1896 translation, "Harmony is to be valued, and an avoidance of wanton opposition to be honoured." Later articles urge officials to revere Buddhism, obey the sovereign and decide important matters through discussion. Some historians doubt that Shotoku wrote it, or that it is as old as claimed, since it survives only in a chronicle compiled a century later.

Building a state on the Chinese model

In 645 a prince and his ally Nakatomi no Kamatari murdered the head of the Soga clan at court. The new leaders announced the Taika Reforms, which aimed to place land and people under the throne, replacing the private holdings of clans with state allotments, censuses and taxes. A defeat in 663, when Japanese and Baekje forces were crushed at sea by Tang China and the Korean kingdom of Silla, sharpened the urgency. Rulers built forts, adopted the title tenno ("heavenly sovereign") and began calling the country Nihon, "origin of the sun." The Taiho Code of 701 set up ministries, provinces and ranks on the Tang pattern. In 710 the court settled at Nara, a capital laid out on a grid that copied Chang'an, the Tang capital. Two chronicles, the Kojiki of 712 and the Nihon shoki of 720, traced the ruling house back to the sun goddess Amaterasu, joining myth to political claim. Emperor Shomu built a giant bronze statue of the Buddha at Todaiji, dedicated in 752, and ordered temples in every province, treating Buddhism as a protector of the state.

The Heian court and the Fujiwara

In 794 Emperor Kammu moved the capital to Heian-kyo, today's Kyoto, which remained the imperial seat until 1869. Over the next centuries, real power slipped from emperors to the descendants of Kamatari, now called the Fujiwara. The Fujiwara held power by marrying their daughters into the imperial line, then serving as regents for the young emperors who were their grandsons. The court also changed how Japan wrote. Chinese characters fit the Japanese language poorly, so scribes developed kana, phonetic scripts made from simplified Chinese characters. Court women, expected to leave Chinese learning to men, wrote in kana and produced some of the world's earliest prose masterpieces, including Sei Shonagon's Pillow Book, a witty catalogue of court life. Meanwhile the land system decayed. Nobles and temples gathered shoen, private estates that escaped taxes, and provincial families took up arms to guard them. From 1086 retired emperors, ruling from behind the throne as "cloistered" sovereigns, competed with the Fujiwara, and both came to depend on warriors.

Worked example: how Fujiwara no Michinaga ruled without a throne

Fujiwara no Michinaga (966 to 1028) never became emperor and for most of his life did not hold the formal post of regent, yet he dominated the court for some thirty years. How? Look at his family tree. Michinaga placed four daughters as consorts of emperors. Three emperors were his grandsons or sons in law. In 1018, at a banquet celebrating the third daughter's elevation to empress, he composed a short poem boasting that the world was his, like a full moon with nothing missing. The Taiho Code said nothing about grandfathers ruling through marriage. Its offices still existed, but they had become stages on which the real game, kinship, was played. This pattern of a sacred emperor who reigns while others rule would recur for centuries, with regents, then shoguns, then cabinets and generals doing the governing. It helps explain how the imperial line survived so long: by rarely holding power directly, it was rarely blamed when power was misused. It also shows a lasting historical lesson: to understand who governs, look past the titles in the law to how decisions are actually made.