This is a catch-all phrase used to describe a large number of upriver tribes; the phrase orang ulu literally means "upriver people."

The various Orang Ulu groups collectively number about 100,000 and form roughly 5.5% of Sarawak's population. The description "Orang Ulu" was originally given to the major Kayan and Kenyah tribes, both of whom live in the Upper Rejang and Upper Baram, and smaller neighbouring groups including the Kajang, Kejaman, Punan, Ukit, and Penan.

The definition has been expanded, however, to include mid and down-river groups with cultural similarities - such as the Lun Bawang, Lun Dayeh, Murut and Berawan - and the plateau-dwelling people of the Kelabit Highlands.

The vast majority of Orang Ulu are Christians, of various denominations, but old animistic beliefs still persist in some areas, along with Bungan, a modern adaptation of traditional religions.

The Orang Ulu are probably Borneo's most artistic people; their massive longhouses are ornately decorated with murals and superb woodcarvings, their utensils are embellished with intricate beadwork, and aristocratic ladies cover their hands, arms, legs and feet with finely detailed tattoos.

Orang Ulu are also fine musicians; once experienced, their plaintive praise-songs are never forgotten, and the haunting melody of the mandolin-like sape can be heard in most Kayan and Kenyah longhouses. Orang Ulu longhouses attract few visitors because of their remoteness, but specialist tour operators offer upriver safaris, and adventurous independent travellers are starting to discover the charms of these warm and hospitable people.