Northern Fujiwara
In the late Heian period, almost the entirety of the Tōhoku region was ruled by the Northern Fujiwara clan. Relatives of the Northern Fujiwara clan, the was given domain over nearly the entirety of present-day Fukushima Prefecture's centrally-located Nakadōri area and eventually expanded their control to include Aizu to the west as well. It is said that the Shinobu Satō clan is one of the reasons for the Satō surname spreading throughout and eventually becoming the most common surname in Japan.