Although the Ashikaga shogunate had retained the structure of the Kamakura bakufu and instituted a warrior government based on the same social economic rights and obligations established by the Hōjō with the Jōei Code in 1232, it failed to win the loyalty of many daimyo, especially those whose domains were far from Kyoto. As trade with China grew, the economy developed, and the use of money became widespread as markets and commercial cities appeared. This, combined with developments in agriculture and small-scale trading, led to the desire for greater local autonomy throughout all levels of the social hierarchy. As early as the beginning of the 15th century, suffering and misery caused by natural disasters such as earthquakes and famines often served to trigger armed uprisings by farmers weary of debt and taxes. The Sengoku period consisted of different periods of fission and fusion.
The Ōnin War (1467–1477), a conflict rooted in economic distress and brought on by a dispute over shogunal succession, is generally regarded as the onset of the Sengoku-jidai. The "eastern" army of the Hosokawa family and its allies clashed with the "western" army of the Yamana, and fighting in and around Kyoto lasted for nearly 11 years, after which it spread to outlying provinces.
Well organized religious groups also gained political power at this time by uniting farmers in resistance and rebellion against the rule of the daimyo. The monks of the Buddhist True Pure Land sect formed numerous Ikkō-ikki, the most successful of which, in Kaga Province remained independent for nearly 100 years.
After nearly a century and a half of political instability and warfare, Japan was on the verge of unification by Oda Nobunaga, who had emerged from obscurity in the province of Owari (present-day Aichi Prefecture) to dominate central Japan, when in 1582 Nobunaga himself fell victim to the treachery of one of his own generals, Akechi Mitsuhide. This in turn provided Toyotomi Hideyoshi, who had risen through the ranks from ashigaru (footsoldier) to become one of Nobunaga's most trusted generals, with the opportunity to establish himself as Nobunaga's successor. Hideyoshi eventually consolidated his control over the remaining daimyo, and although he was ineligible for the title of Seii Taishogun because of his common birth, ruled as Kampaku.
When, in 1598, Hideyoshi died without leaving a capable successor, the country was once again thrust into political turmoil, and this time it was Tokugawa Ieyasu who took advantage of the opportunity.
Hideyoshi had on his deathbed appointed a group of the most powerful lords in Japan — Tokugawa, Maeda, Ukita, Uesugi, Mōri — to govern as the Council of Five Regents until his infant son, Hideyori, came of age. An uneasy peace lasted until the death of Maeda Toshiie in 1599. Thereafter, Ishida Mitsunari accused Ieyasu of disloyalty to the Toyotomi name, precipitating a crisis that led to the Battle of Sekigahara. Generally regarded as the last major conflict of the sengoku-jidai, Ieyasu's victory at Sekigahara marked the end of the Toyotomi reign. Three years later, Ieyasu received the title Seii Taishogun, and established Japan's final shogunate, which lasted until the Meiji Restoration in 1868.
The contrasting personalities of the three leaders who contributed the most to Japan's final unification—Nobunaga, Hideyoshi, and Ieyasu—are encapsulated in a series of three well known senryu:
Nobunaga, known for his ruthlessness, is the subject of the first; Hideyoshi, known for his resourcefulness, is the subject of the second; and Ieyasu, known for his perseverance, is the subject of the third verse.
Other notable daimyos include: