Northern Fujiwara
The Northern Fujiwara (奥州藤原氏 Ōshū Fujiwara-shi) were a Japanese noble family that ruled the Tōhoku region (the northeast of Honshū) of Japan from the 12th to the 13th centuries as if it were their own realm. They succeeded the semi-independent Emishi families of the 11th century who were gradually brought down by the Minamoto clan loyal to the Imperial throne based in Kyoto. Ultimately they were conquered by the Kantō samurai clans led by Minamoto no Yoritomo.
During the 12th Century, at the zenith of their rule, they attracted a number of artisans from Kyoto and created a capital city, Hiraizumi, in what is now Iwate prefecture. They ruled over an independent region that derived its wealth from gold mining, horse trading and as middlemen in the trade in luxury items from continental Asian states and from the far northern Emishi and Ainu people. They were able to keep their independence vis-a-vis Kyoto by the strength of their warrior bands until they were overwhelmed by Minamoto no Yoritomo in 1189.
Below is a family tree of the Fujiwaras who show up most frequently in historical accounts.
Tsunekiyo (経清) ┃ Kiyohira (清衡) ┣━━━━━━━━━━━┓ Koretsune (惟常) Motohira (基衡) ┃ Hidehira (秀衡) ┃ ┏━━━━━━━━━━━┳━━━━━━━━━━┳━━━━━━━━━━━┓ Kunihira (国衡) Yasuhira (泰衡) Tadahira* (忠衡) Takahira (高衡)
*a.k.a. Izumi (no) Saburo
(Bold lines indicate natural kinship. Adopted kin are not shown.)