Also known as the Warring States Period, was a turbulent and violent period of Japanese history when rival warlords or daimyo fought bitterly for control of Japan. The fighting in the 16th century would eventually reduce the warlords to only a few hundred in number as the country was effectively carved up into princedoms. Eventually, one warlord rose above all his rivals: Oda Nobunaga, who set Japan on the road to unification from 1568 CE.
The Ashikaga Shogunate (1338-1573 CE) held control of the central part of Japan, and the bureaucracy at the capital was relatively efficient, but the outer provinces were left semi-independent as local warlords or daimyo ruled their own lands how they saw fit. Local officials and estate managers such as the jito found it much more difficult to secure the taxes the state was due from landlords who now had no fear of any government reprisals. The daimyo (literally 'Great Names') were feudal lords who commanded personal armies of samurai or anyone else willing to take up arms and defend their lord's estates and help expand it.
The warlords passed on their position of strength to their male heir and so the position of daimyo became hereditary unless challenged by ambitious subordinate commanders. The wealth of the daimyo came from commerce, trade, and taxes imposed on those peasants who farmed on their estates. Daimyo may have been a law unto themselves but many of them did formulate law codes to better regulate the sometimes thousands of people under their command. These laws could cover anything from the prohibition of building castles and fortifications in their territory to measures that avoided wasting money on expensive theatre actors brought in from outside the daimyo's domain.
Villages grew in number and size as farmers sought security in numbers and worked together to produce more and benefit from communal projects such as digging irrigation channels and building waterwheels. In the absence of any authority from the central government, many villages governed themselves. Small councils or so were formed, which made decisions regarding laws and punishments, organized community festivals, and decided on regulations within the community. Some villages got together to form leagues or ikki for their mutual benefit, with some even challenging and winning battles against local daimyo, while others at least took advantage of their lord's absence on campaign to better the lot of the peasantry. There were several major peasant revolts, too, notably in Yamashiro province between 1485 and 1493 CE.
Japan continued to mix Buddhism and Shinto with traditional beliefs throughout the medieval period. New forms of Zen Buddhism were introduced from China where various local sects simplified the religion and stressed that enlightenment and advancement to heaven were open to all regardless of social status. Zen principles of austerity and restraint became very popular with samurai. Another popular Buddhist sect was Nicheren, founded by the monk of the same name (1222-1282 CE), which stressed the importance of chanting from the Lotus Sutra holy text. Buddhist monasteries were important providers of education to all classes and many hosted schools of artists of all kinds.
Gyokusenji Temple was built in 1251 by Ryonenhomyo, a buddhist priest born in Korea who trained in ascetic practices at the Kinzan Temple in China. He built many halls that enshrine Buddhist statues, establishing the basis for Zen Buddhism in the process.
Economically, the country prospered as agricultural techniques improved (e.g. double-cropping, better iron tools, fertilizers and hardier strains of rice were all employed). Trades became more specialized and were governed by guilds, while trade with China boomed with Japanese gold, swords, and timber exchanged for silk, porcelain, and copper coinage amongst other things. Villages began to grow in size as the road networks improved and small businesses and markets made them more attractive and convenient places to live.
In the 14th century Japanese feudal leaders began to send large trading expeditions to China and Korea. When denied trading privileges, the Japanese were quick to resort to violence to ensure their profits. By the 14th century, piracy had reached serious proportions in Korean waters. It gradually declined after 1443, when the Koreans made a treaty with various Japanese feudal leaders, permitting the entry of 50 Japanese trade ships per year, a number that was gradually increased. In the 15th century CE, Korea would also trade with Japan, exporting cotton and ginseng, in particular.
Japan was wholly dominated by its warriors in the medieval period, and this situation was reflected in its austere domestic architecture and interior decor, its art, and literature. The minimalism of Zen Buddhism would have a significant influence on calligraphy and ink painting, epitomized by the work of the Zen priest Sesshu (real name Toyo, 1420-1506 CE) who specialized in suiboku - black ink and water on white paper scrolls, in a style that has been described as an austere form of impressionism. Performance art was one of the lasting products of the medieval period. Noh (Nō) theatre developed from the 14th century CE and derived from older dance and music rituals performed at temples and shrines. In Noh, mask-wearing male actors made highly stylised movements accompanied by music with some brief spoken words to explain the general story which told of gods, demons, and heroes, and their various moral predicaments. The extravagant and richly embroidered costumes of the actors would greatly influence late medieval and early modern fashion in Japan.
Excerpt derived from Encyclopedia Britannica and World History Encyclopedia