The Amago clan (尼子氏 Amago-shi), descended from the Emperor Uda (868-897) by the Sasaki clan (Uda-Genji).
Sasaki Takahisa in the 14th century, having lost his parents at the age of three years, he was brought up by a nun ( ama in Japanese). He was the first to take the name of Amago (nun's son) in her memory.
The Amago fought the Ōuchi clan or the Mōri clan (who had been among their vassals), during Japan's Sengoku period.
Amago Tsunehisa (1458-1541), great grandson of Takahisa inherited from his father Kiyosada and his grandfather Mochihisa the office of shugo of Izumo Province and resided at the castle of Toda.
For much of the next hundred years, the clan battled with the Ōuchi and Mōri, who controlled neighboring provinces, and fell into decline when Tomita castle fell to the Mōri in 1566.
Amago Katsuhisa tried to regain prestige for the clan by joining the forces of Oda Nobunaga, invaded Tajima and Inaba provinces, but was defeated and died in the Siege of Kōzuki by the Mōri in 1578.
The Amago's chief generals were called Amago 10 Yushi (尼子十勇士).