The story
After a Japanese place name in Kyūshū, 薩摩 (さつま, Satsuma), from where it was first exported to the west.
Etymology from Wiktionary, CC BY-SA 4.0.
satsuma
sat·su·maToday it means: A seedless and easy-peeling cultivar of mandarin orange of Japanese origin; Citrus unshiu. Full definition →