The Fujiwara clan--actually one of the classical uji--was created in the 7th century. They rose to power and prominence in Nara and Heian period Japan, with the Northern Fujiwara effectively controlling the reigns of power during the transition from the Ritsuryo system of government. The period during their height, when they effectively controlled the Imperial throne through careful political manipulation and "marriage politics", is sometimes referred to as the Fujiwara Period.
History
The formation of the Fujiwara
The first member of the Fujiwara family was Nakatomi Kamatari (614-669), who was granted the name for his service to the throne, including the assassination of the Soga chieftain in 645. The Nakatomi family were a provincial family, possibly descended from the Emishi chieftains in eastern Japan that were incorporated into the Yamato polity. They appear to have had a major influence in Hitachi Province, where they were responsible for the prominence of Kashima Jingu, a major shrine with an imperial grant overseen by the Nakatomi since at least 645. Though Kamatari is thought to have come from Fujiwara in the Kinai, some records say he was originally from Hitachi, though this probably was more true of his immediate ancestors.
The Nakatomi had created a power base for themselves as court ritualists. It is interesting to note that they are hardly to be found in the Kojiki, but appear much more often in the later Nihongi, possibly indicating their rise to power and a desire to legitimize their position.
Fujiwara Kamatari's sons continued to bear his name. Perhaps the most famous is Fujiwara Fuhito (659-720), who was only 10 years old when his father died. Three years later, the Jishin War broke out in 672, and Prince Oama succeeded to the throne. The Nakatomi and their descendants fell into disfavor, and Fuhito appears to have been taken in by a scribe (fuhito) named Tanabe Osumi in Yamashina.
In 689, Fuhito was appointed a judge, and from there his fortunes took a turn for the better. He was chosen by Empress Jito (r. 690-697) to aid her after the death of her husband, and later as the guardian of her son, who would eventually become Emperor Mommu. Fuhito's daughter, Miyako, was chosen, along with two other women, as a consort for Mommu in 698. After Mommu's death in 707, Fuhito was made Minister of the Right (Udaijin) by Empress Gemmei (formerly Empress Jito). This gave him tremendous power over the administration of the ritsuryo code, which he had helped implement.
Fuhito's sons included Maro (695-737), Umakai (694-737), Fusasaki (681-737), and Muchimaro (680-737), who would become the progenitors of the Capital, Ceremonial, Northern, and Southern branches of the Fujiwara family, respectively.
Early Fujiwara Regency
Fujiwara Fusasaki's lineage grew and continued to accumulate wealth in the capital and provinces, including his son Fujiwara Matate (706-764) and grandson Fujiwara Uchimaro (756-812), who, along with another member of the Northern lineage, Fujiwara Sonohito (756-818), served as an influential member of the Council of State. However, it would be Uchimaro's son, Fujiwara Fuyutsugu (775-826), who would really be seen as the start of a new age of Fujiwara power and influence.
Fuyutsugu served Emperor Saga while he was still Crown Prince Kamino. Fuyutsugu's posthumous biography described him as extremely capable in matters of both military and civil administration. He appears to have been quite sociable and reportedly benevolent. He became director of the Royal Secretariat along with Kose Notori when that office was established in 810, and then joined the Council of State as an advisor the following year. He eventually rose to become Minister of the Right after Sonohito's death.
Fuyutsugu became inextricably connected with the royal line when his daughter, Nobuko (alt. read Junshi), became the senior consort of Saga's son, Prince Masanaga (later Emperor Nimmyo), while Saga's daughter, Minamoto Kiyohime, became a consort of Fuyutsugu's son, Yoshifusa (804-872). Fuyutsugu's grandson, Prince Michiyasu, would eventually come to the throne as Emperor Montoku, but not before the former's death. Fuyutsugu was posthumously granted the supreme role of Prime Minister (Dajodaijin). With the Fujiwara and Imperial lines so co-mingled, this set the stage for a period of regency by the scions of the Fujiwara family.
After the death of Saga In in 842, reports surfaced of a planned coup by supporters of Crown Prince Tsunesada, son of Emperor Junna and his queen-consort, Princess Masako, later known as the Jowa Coup. Those accused were sent into exile, including Tomo Kowamine and Tachibana Hayanari, and Prince Michiyasu became the new Crown Prince, eventually reigning as Emperor Montoku. There seems to have been little motive for Prince Tsunesada in this coup, and suspicion has since fallen on Michiyasu's uncle, Yoshifusa, as well as his grandmother, Tachibana Kachiko (786-850). The resulting power vacuum left Yoshifusa the senior member of the Council of State. In 848, he was named Minister of the Right and began acting as the leader of the Council, despite the presence of Minamoto Tokiwa as Minister of the Left (Sadaijin). In 857 he was formally named Prime Minister. In addition to all of this, his daughter Akirakeiko was Montoku's queen-consort, allowing Yoshifusa a great deal of sway in the politics during Montoku's reign.
In 858, Montoku died. His successor was 9 year old Korehito, later known as Emperor Seiwa (r. 856-876). Yoshifusa was designated as regent for the young Seiwa until he came of age. While the official term sessho was not yet in use, this was effectively the office Yoshifusa now held. This regency should have ended in 864, but that was interrupted by the Otenmon Coup, when the Otenmon gate burned down. Arson was suspected, and senior counselor Tomo Yoshio and Yoshifusa's son, Minister of the Right Fujiwara Yoshimi came under suspicion. Minister of the Left Minamoto Makoto was also suspected and agents were sent to arrest him. Yoshifusa, on learning about it, entered the royal presence and found that the agents were not sent by an imperial command. He freed Tomo, Minamoto, and others who had been arrested. Later, however, new accusations arose against Tomo Yoshio and his son, Nakatsune, and their property was confiscated and they were sent into exile.
During this turbulent period, Seiwa ordered Yoshifusa to "carry out governance of the realm". He was given authority over the Council of State, authority that would later be codified in the office of kanpaku. Yoshifusa used this power to reign in independent-minded nobles.
Yoshifusa died in 872, and he was not immediately succeeded. However, when Seiwa retired in 876, his successor was again a minor--nine year old Prince Sadaakira (Emperor Yozei), son of Fujiwara Takaiko who was sister to Fujiwara Mototsune (836-891), Yoshifusa's adopted son and heir. Mototsune, who was at that time Minister of the Right, was appointed regent for his grandson as Yoshifusa had been for Seiwa, surpassing then Minister of the Left Minamoto Toru. Mototsune became Prime Minister four years later in 880, from which point on he is termed kanpaku in the official documents, although the first extant use of the term would come in 884, when Yozei was removed from the throne and Emperor Koko succeeded him. Emperor Koko's edict directing Mototsune to continue to aid in the affairs of state would name Mototsune as kanpaku.
When Emperor Uda came to the throne, he attempted to continue utilizing Mototsune in the same way, but without an official promotion to the position of kanpaku. Mototsune refused, and eventually won out in what has come to be known as the Ako Affair. This left Emperor Uda bitter, however, and Mototsune's son Fujiwara Tokihira (871-909) did not find great favor in the Emperor after his father's death. Tokihira nevertheless held power as the Minister of the Left, although Uda appointed his own advisor, Sugawara Michizane (845-903) as Minister of the Right as a foil to Fujiwara power and influence, which had already grown so great that many officials were complaining one couldn't get an appointment without their backing.
Michizane was an able politician, but eventually his power waned. Emperor Daigo succeeded Uda, and was more friendly to Tokhira, who had Michizane exiled to the Dazaifu in 901, where he died shortly after. Tokihira followed soon after in 909. His brother, Fujiwara Tadahira (880-949), would not succeed him as leading member of the Council of State until Minister of the Right Minamoto Hikaru's death in 913. Tadahira never enjoyed the same relationship with Daigo that his brother had, but his power grew durin the Encho era. He was named Minister of the Left in 924, and became Regent in 930, when Daigo abdicated for the three year old Emperor Suzaku. He became Prime Minister in 936, and eventually resigned as regent to be named kanpaku.
Later Fujiwara Regency
After Tadahira's death, no regent was named for Emperor Murakami. However, it became common practice from the time of Emperor Reizei (r. 967-969) onwards. This later period is often seen as the mature regency, as the Fujiwara had consolidated their power base and position within the court.
References
Piggott, Joan R. ed. Capital and Countryside in Japan, 300-1180, University of Cornell, NY, 2006.