Pa’ Umor village derived its name from a river tributary of Pa’ Debpur, where the community previously resided. This settlement had at some point merged with the village of Pa’ Terap, and included the people from the present village of Pa’ Ukat. Some of the people from Pa’ Terap formed the village of Pa’ Lungan.
Until the 1960s, Pa’ Umor people had traditionally practiced swidden farming (shifting cultivation). They farmed the plains of Pa’ Debpur and its tributaries. Therefore, they had lived in a number of different longhouses. According to Pa’ Umor informants, there were at least 19 previous longhouse sites, each named after the river system (pa’ or arur) or the river confluence (lung), going back five or six generations. The settlement moved to the present location in 1980, which used to be a small airstrip built to accommodate the small missionary airplane that served the needs of local people in the 70’s.