The tradition is theirs, but the name is Japanese.
Loretta deBrum of the Marshall Islands Visitors Authority said that before the Marshallese adapted the Japanese word "amimono" to refer to handicrafts, they used the local word "monakjen."
The Japanese word came into use while Japan occupied the Marshall Islands, a nation in the heart of the Pacific near the Equator, in the early part of the 20th century.