Surviving the Genpei War (1180–1185), he was adopted by Hōjō Tokimasa, changed his name to Tokinobu (時信) and was given the island of Tanegashima at the beginning of the Kamakura period.

The Tanegashima clan enjoyed a high degree of autonomy until Shimazu unified southern Kyūshū in the late 16th century.

In 1424, however, Tanegashima was forced to give Kuchierabu back to the Ōshū family although it regained the island three years later.

In 1543, Tadatoki's son Shigetoki was attacked by Nejime Shigetake, a ruler of Ōsumi Province, and fled to Tanegashima.

[1] Tanegashima Tokiuji, Tadatoki's father, established a channel of communication to Kinai (central Japan).

In the 1460s the population of Tanegashima, Yakushima and Kuchierabu converted en masse to the Hokke sect of Nichiren Buddhism.

Historical sources show that gifts dedicated to Honnō-ji by Tanegashima Tokiuji included Chinese and South Asian products such as silk fabric and pepper.

[3] Tanegashima Island functioned as a relay station of one of the main routes of Chinese trade that connected Sakai to Ningbo.

It is known that Japanese trade ships to Ming China exported Southeast Asian products such as pepper and sappanwood.

[3] Tanegashima is traditionally known as the site of the introduction of European firearms to Japan although this account is frequently questioned by historians.

When Hisatoki died in 1612 leaving his successor in the mother's womb, Shimazu intervened in Tanegashima's governance, making it a dutiful subject.