The most important numerically are the Dyaks, the Dusuns and Muruts of the interior, the Malays, among whom must be counted such Malayan tribes as the Bajaus, Ilanuns, &c., the Bugis, who were originally immigrants from Celebes, and the Chinese.
Accounts of the Malays, Dyaks and Bugis are given under their several headings, and some information concerning the Dusuns and Muruts will be found in the section below, which deals with British North Borneo.
The seashore and the country bordering closely on the west coast are inhabited chiefly by Dusuns, by Kadayans, by Bajaus and Ilanuns - both Malayan tribes - and by Brunei Malays.
The interior is dotted with infrequent villages inhabited by Dusuns or by Muruts, a village ordinarily consisting of a single long hut divided up into cubicles, one for the use of each family, opening out on to a common verandah along which the skulls captured by the tribe are festooned.
It has been customary to speak of these tribes as belonging to the Dyak group, but the Muruts would certainly seem to be the representatives of the aboriginal inhabitants of the island, and there is much reason to think that the Dusuns also must be classed as distinct from the Dyaks.
Dusuns and Muruts alike are in a very low state of civilization, and both indulge inordinately in the use of intoxicating liquors of their own manufacture.
The Roman Catholic mission maintains an orphanage, a church and school at Sandakan, and has missions among the Dusuns at several points on the west coast and in the Tambunan country.