Shikanoshima Island, the home base of the Azumi-tribe, is very famous as a place where a gold seal was discoverd. In the gold seal, there were five Chinese characters carved. “ 漢委奴國王 ”( Kan no Wa no Na no Kokuou, i.e. king of the Na state of the Wa 〔vassal〕 of Han Dynasty ).
漢( Kan ) was representing the Han Dynasty. 委(倭）奴( Wa no Na ) mentioned the Na tribe among Wa ( Japanese ) race. The last two-letter word 國王 ( Kokuou ) was the highest of the 5 ranks that were used to grade external tributary rulers of the Han Dynasty. However, the seal system was one of the diplomatic policies of the Han Dynasty in China ( 206BC - 220AD ). It didn't neccessarily mean the Na state was directly governed by the dynasty.
The Chinese chronicle titled “ Hou Han Shu ( 後漢書 History of the Later Han Dynasty ) ” says, “ The Na state of the Eastern tribe in Wa ( Japan ) sent a messenger with tribute to the emperor in 57AD. The messenger introduced himself as a high official. The state lies in the south of Wa. The emperor Guanwu ( 光武帝 ) conferred a seal with a tassel. ” Also, there was a record the messenger of the Na state said the people of his state were “ descendants of Taibo ( 太伯 )”.
This Taibo was a legendary person who was said to be the Father of Wu ( 呉 ) state at the Spring and Autumn Period in Chinese history. There would be a big possibility that we could imagine the Azumi-tribe, who had a deep connection with mainland China and had power around Shikanoshima Island, founded the Na state in the area of Kita-Kyushu ( Northern Kyushu ). And they sent messenger to the Han Dynasty afterwards.
Azumi-tribe with thier highly developed skill for voyaging enlarged thier influential territory to all parts of Japan and left place names associated with Azumi-tribe in each place. Azumino in Shinshu is one of them.