Under the early courts, when military conscription was centralizedly managed, military concerns were removed from the hands of the provincial nobility and given to the central government to manage. After 792, however, the system began to fall apart, and the people who held local control once again became the major source of military might. Shoen holders had access to manpower, and as they obtained improved military technology (such as new training methods, more powerful bows, armour, horses, and superior swords) and faced worsening local conditions in the ninth century, military service became an integral part of the life of shoen holders. Shoen holders had access to manpower. In order to better defend themselves, not only the shoen but also civic and religious organisations organised private security squads. The provincial upper class was gradually converted into a new military elite based on the principles of the bushi (warrior) or samurai (literally, one who serves). These beliefs were founded on the samurai code of honour.
The interests of the Bushi were varied, and they crossed through the established power structures of the time to create new groups in the eleventh century. Consolidation of shared interests, familial relationships, and familial kinship occurred among military groupings that eventually formed an integral aspect of family administration. Over the course of time, big military families from around the area gathered around members of the court nobility who had become influential leaders in the province. These military families were allowed access to manpower and acquired status as a result of their links to the imperial court. In addition, the court awarded them military titles. The Fujiwara, Taira, and Minamoto families were three of the most influential in Japan at the time and had backing from the emerging military elite.
A decrease in food production, an increase in population, and increased competition for resources among the great families all contributed to the gradual decline of Fujiwara power and gave rise to military upheavals in the middle of the tenth and eleventh centuries. These factors also led to an increase in the number of wars that broke out during this time period. Members of the Fujiwara, Taira, and Minamoto families, all of whom had descended from the imperial family, attacked one another, claimed control over vast tracts of conquered land, set up rival regimes, and generally broke the peace in the Land of the Rising Sun. The Fujiwara, Taira, and Minamoto families were all descended from the imperial family.
The Fujiwara were the ones who had control of the throne up to the reign of Emperor Go-sanjo (1068-73), who was the first emperor since the ninth century who was not born of a Fujiwara mother. Reforms were put into place by Go-Sanjo to limit the power of the Fujiwara family because he was adamant about regaining imperial sovereignty via strong personal leadership. In addition to this, he set up an office with the intention of consolidating and verifying the estate’s documents in order to restore central authority. There were many shoen that lacked the appropriate certification, and wealthy landholders such as the Fujiwara felt as if they were in danger of losing their properties. Go-Sanjo was also responsible for establishing the Incho, commonly known as the Office of the Cloistered Emperor. This position was held by a line of emperors who had abdicated their thrones in order to focus on insei, or administration behind the scenes (cloistered government).
The loss of the Fujiwara’s influence allowed the Incho to step in and fill the hole it created. Instead of being exiled, the Fujiwara were largely allowed to continue serving in their previous roles as civil dictator and minister of the centre, but they were not involved in the decision-making process. Over the course of time, a significant number of Fujiwara were succeeded, mostly by members of the ascendant Minamoto family. While the Fujiwara fought amongst themselves and split into northern and southern divisions, the insei system enabled the paternal line of the imperial family to acquire control over the throne. This occurred while the Fujiwara were engaged in internal conflict. The years 1086 through 1156 were known as the era of dominance of the Inco and the emergence of the country’s military elite across the whole of the nation. Instead of being based on civil authority, the government was ruled by military strength.
Around the middle of the twelfth century, a fight for succession provided the Fujiwara with a chance to restore the authority they had previously held. In the bloody conflict that broke out in 1158, Fujiwara Yorinaga fought on the side of the deposed emperor against the heir apparent, who had the backing of the Taira and the Minamoto families. In the end, the Fujiwara were eradicated, the previous method of administration was replaced, and the insei system was rendered useless as bushi assumed control of court matters, marking a turning point in the annals of Japanese history. Within a year, a conflict between the Taira and the Minamoto occurred, which marked the beginning of a twenty-year era in which the Taira were dominant. The Taira were easily distracted by court life and paid little attention to issues plaguing the provinces. Finally, Minamoto Yoritomo (1147-99) rose from his base in Kamakura (in the Kanto area, southwest of contemporary Tokyo) to destroy the Taira, and with them the young emperor they held, in the Genpei War. He did this from his position in the Kanto region, southwest of modern Tokyo (1180-85).