Notes

Malaysia has multiracial with many different ethnic groups.These are including Malays,Chinese,Bumiputara Group,Indians and others...
Approx. Share of Population
%50 Malay
Malays more than other ethnic groups.Their language is mother-language and formal lang of country.Malays are in general muslim.Malay government going islamization policy.
%22 Chinese
Chinese people second in terms of population.They are immigrated from China 19th century.Chinese merchants are popular because they are special skill for trade.
%7 Indians
Colonial era-Labors for bad works and they are working low-paid and low life standart.
%10 Bumiputara group
Its mean sarawak people.they are some aboriginal group.they are free of tax
%11 Others..
This context going a rich country about food,culture,religon.

The colonial period of starting was coming Dutch and portuguese.The dutch has more powerful guns and lobbying portuguese so dutch dominate portuguese.Dutch traders and merchants dominating economy market and dutch politicians take turn indonesian policy and a new company born.Its name Dutch east indian company try to takeover to spice trade on Indonesia and it was successful and the company is fastly huge but it bankrupt in 1799 and nationalized by dutch state because of british-napaleon profit on the Java land.So dutch colonialism effect to trigger to entrance of christianity on the indonesian people and little cultural assimilation effect on mother language.

Firstly,brunei is a small country on the map over the malaysia and under the south china sea but its economy huge.Brunei didnt invaded like malaysia and indonesia.This reason is Brunei attached british in foreign affairs.Brunei has important goldfield.Brunei have rich oil rezerve and brunei can operate this rezerves not need other countries and sell to all around world countries.In short, Brunei economy developed because its protect british expoilatition.Brunei members of ASEAN and APEC it might help develop to economy.Brunei have mixed economy.

Yes,i think Muslim merchants contributed Islam on Southeast Asia.Muslim merchants have good morals and honest advice due to Quran.So islam was spread wherever they go.In this way people of many countries accepted islam and became muslim