Malay is a term used to refer to the coastal people and the people of the King/Sultan in Malay archipelago. After Islamisation of this region, Malay had been highly associated with Islam, and for those who embraced Islam were also called Masuk Melayu (although this is not necessarily true or compulsory). This trend lasted until post-colonial era whereby in modern time, anyone who embrace Islam are not required to "Masuk Melayu" or identify as Malay any more.
Below are the coastal people of Borneo:
1. Sarawakian Malay
2. Sambas Malay
3. Pontianak Malay
4. Pembuang Malay
5. Sampit Malay
6. Banjar (Malay)
7. Pasir Malay
8. Kutai Malay
9. Berau Malay
10. Bulungan Malay
11. Tidung Malay
12. Bajau
13. Suluk
14. Bisayan
15. Kedayan
16. Brunein Malay
17. Melano
1. Sarawakian Malay
2. Sambas Malay
3. Pontianak Malay
4. Pembuang Malay
5. Sampit Malay
6. Banjar (Malay)
7. Pasir Malay
8. Kutai Malay
9. Berau Malay
10. Bulungan Malay
11. Tidung Malay
12. Bajau
13. Suluk
14. Bisayan
15. Kedayan
16. Brunein Malay
17. Melano
Although some of them do not have "Malay" word in their ethnics name, they are actually Malay. For example, Banjar and Kedayan. They speak languages very close to Malay (both belonging to Malayan group) and have a closer customs like Malay. And some of the ethnics mentioned above are sometimes considered as Malay, like Suluk and Bajau, most probably due to their same faith as the rest of ethnic Malays; i.e. Islam. However, they are not ethnically Malay as their languages are quite far from Malay. They belong to Visayan and Bajaw-Sama groups respectively (both belong to the Philippines group). Some of the Malay people like Tidung Malay, Bulungan Malay, Kutai Malay, Banjar and many more were actually Dayak tribes who had previously reverted to Islam en mass and adopted the title Malay to represent their ethnicity.
Dayak is a collective term used to classify non-coastal and non-Malay native ethnics in Borneo. Dayak word originated from Kenyah language which mean upstream of the river or interior. Some people claimed that the word Dayak means human in Ibanese. Daya in Kanayatn language means land people (Orang Darat). Meanwhile, Daya in Malay means force or power or gravity. Banjar people on the other hand, used to call Dayak as Biaju which literally means "from the upstream area".
Although Dayak are considered as a group of ethnics, they do not speak the same language groups. They are at least, 5 language groups spoken by Dayak; i.e. Malayic group (such as Iban, Bukit, and Mualang), Land Dayak group (such as Bidayuh and Jago), Sabahan group (such as Dusun and Kadazan), Northern Borneon group (such as Murut and Melanau) and Barito group (such as Ngaju and Maanyan).
There are more or less 8 sub-groups within the Dayak. They are:
1. Ngaju group
2. Ibanic group (a.k.a Sea Dayak)
3. Klemantan group (a.k.a. Land Dayak)
4. Apau-Kayan group
5. Murut group
6. Kadazan-Dusun group
7. Punan group
8. Ot Danum group
1. Ngaju group
2. Ibanic group (a.k.a Sea Dayak)
3. Klemantan group (a.k.a. Land Dayak)
4. Apau-Kayan group
5. Murut group
6. Kadazan-Dusun group
7. Punan group
8. Ot Danum group
Ngaju group includes Dayak Ngaju, Dayak Meratus, Dayak Bakumpai, Dayak Mendawai, Dayak Kayahan, Dayak Katingan, Dayak Mengkatip, Dayak Berangas dan Dayak Beraki. The Ngaju and Meratus (or Bukit) tribes had involved in the ethnogenesis of Banjar people. Meanwhile, majority of Dayak Bakumpai is Muslim.
Ibanic group includes Iban, Mualang, Semberuang, Sembaru', Bugau, Air Tabun and Kantu. Iban is the biggest ethnic in Sarawak.
Klemantan group includes Sadong, Bidayuh (Jagoi, Biatah), Sanggau, Benyadu', Lundu, Bekatiq, Ukit and Selako. They are mostly found in Kalimantan Barat, Indonesia and some part of Sarawak.
Apau-Kayan group includes Maloh, Kayan, Kenyah, Busang, Aoheng, Modang and Bahau. Some of the Kayan people who converted to Islam had contributed in the ethnogenesis of Bulungan Malay.
Murut group includes Hill Murut, Lun Dayeh, Kelabit, Berawan, Bookan, Paluan, Tagal Dayak, Kajang and Melanau. Murut groups are genetically closer to Tidung Malay and Bulungan Malay as they were previously Dayak before mass conversion into Islam.
Kadazan-Dusun group includes Bonggi, Bundu, Dumpas, Gana, Garo, Ida'an, Kimaragang, Kolobuan, Kuijau, Lingkabau, Liwan, Lobu, Lundayo, Makiang, Malapi, Mangkaak, Minokok, Paitan, Nabai, Pingas, Rumanau, Rungus, Sinobu, Sonsongon, Sinorupu, Sukang, Sungei, Tatana, Tangara, Tidong (near Brunei-Sabah border), Tindal, Tobilung, Tolinting, Tombonuo, Tuhawon, Tutung, Bisaya and Lotud. The Kadazan-Dusun Association also included Kadayan and Murut tribes as a part of Kadazan-Dusun group. Among of the following, many of Orang Sungei, Bisaya and Kadayan people are Muslims.
Punan group includes Punan (Sajau Hovongan, Penihing, Penyawung, Aput), Bukat and Penan. Most of the unclassified ethnics are grouped under Punan ethnic and it might change in the near future as more evidence would be available for proper grouping of Dayak tribes.
Ot Danum group includes Pawan, Kebahan, Kohin, Sabaung Tamoan, Limbai, Tebidahm Ot Danum, Siang, Maanyan, Luangan/Lawangan, Tunjung, Bentiang and Benuaq. Sometimes, Dayak Ngaju is also included in this group. Dayak Maanyan also played a role in ethnogenesis of Banjar people.
Conclusion:
Nowadays, when people convert into a new religion, they are more keen to retained their original ethnic identity rather than embracing a more dominant ethnic group in their new religion community. Some people of mixed-parental ethnicities might as well embraced both or denouncing one of them or adopting a "new" identity (for example Chindian, Sino-kadazan etc). Ethnicity are influenced and entangled by the following factors: genetics, languages, nationality or statehood, and history. At the end, ethnicity is a self-identification of a person. You are what you want to be and what you identify yourself as.
Nowadays, when people convert into a new religion, they are more keen to retained their original ethnic identity rather than embracing a more dominant ethnic group in their new religion community. Some people of mixed-parental ethnicities might as well embraced both or denouncing one of them or adopting a "new" identity (for example Chindian, Sino-kadazan etc). Ethnicity are influenced and entangled by the following factors: genetics, languages, nationality or statehood, and history. At the end, ethnicity is a self-identification of a person. You are what you want to be and what you identify yourself as.