According to
Tourism Malaysia, there are several Indigenous Ethic Groups in Peninsular Malaysia and also in the states of Sarawak and Sabah located in West Malaysia.

(image credit:
asiaexplorers.com)Orang Asli is the term for the indigenous people found in Peninsular Malaysia. There are 3 main tribal groups: the Negrito, the Senoi and the Proto-Malay. The Negrito generally reside in the north, the Senoi in the middle and the Proto-Malay in the south. Each group or sub-group has its own language and culture. The common occupations are fishermen, farmers while some are semi-nomadic. To learn more about the Orang Asli, refer to this
article.
In Sarawak, the indigenous people are collectively known as the Dayaks. There are over 200 tribal groups with the major ones being the Iban, the Bidayuh and the Orang Ulu. They live in traditional longhouses that can accommodate up to 100 families.
Ibans (30%) make up the biggest of Sarawak's ethnic groups. Not to be confused with the Sea Dayaks, they are skillful with boats as they were a warrior race in the past known for headhunting and piracy. The Ibans worship the Singalung Burung, the bird-god of war. Even though most of them are now Christians, traditional customs are still practised.
The Bidayuh are known for their hospitality and their tuak, which is a rice wine. They are usually farmers and hunters with their homes mostly in the mountainous areas. Being headhunters in the past, they would store their prized skulls in a baruk, which was a roundhouse that stands 1.5 metres above ground. Likewise, most of the Bidayuh have also converted to Christianity.
The Orang Ulu are also known as the upriver tribes of Sarawak. They form roughly 5.5% of the Sarawak population and have over 100,000 different tribes. The Orang Ulu are known for being artistic as their longhouses are elaborately adorned with murals and their woodcravings. Their utensils are also embellished with intricate beadwork. Aristocratic ladies have finely-detailed tattoos on their bodies as well.

(image credit:
sarawakdotcom.blogspot.com)
In Sabah, the three largest indigenous ethnic groups are the Kadazan Dusun, the Bajau and the Murut.
Kadazan Dusuns (30%) make up the largest ethnic group in Sabah. They originally consisted of two tribes, the Kadazan and the Dusun before being grouped together due to the same language and culture they share. Kadazan are mainly inhabitants of flat valley deltas while the Dusun normally lived in the hilly mountainous areas of inner Sabah.
Bajaus (15%) are the second largest ethnic group in Sabah. They were historically nomadic sea-faring people that worshipped the Omboh Dilaut, thus they were sometimes known as the Sea Gypsies. The Bajaus who chose to abandon their sea-faring roots became farmers and cattle-breeders.
Muruts traditionally lived in the northern inland areas of Borneo and they were the last of the Sabah's ethnic groups to renounce headhunting. These days, they are mostly shifting cultivators of hill paddy and tapioca. Blowpipe hunting and fishing supplement their diet.