1) Domain of Japan 
During the Edo period, Aizu was a feudal domain known as Aizu-han. It was part of Mutsu Province; the area once was part of Iwase Province in the 700s and, before the prefectural system, Iwashiro Province. Although never an official province in its own right, Aizu was considered as such de facto, and even today local Japan Rail stations prefix `A....