Indonesia has been considered as one of the ethnically diverse country in the the world. There are more than 1000 Indonesia ethnics group living in the archipelago.
Probably some other sources mentioned fewer but this is quite updated data from Indonesia Central Bureau of Statistics. The difference may come from the facts that the census made in 2010 includes also the sub and sub sub ethnics.
The census found that there were at least more than 600 big ethnic groups up to 2010.
Javanese ethnics with more than 94 millions has a share of more than 40% of Indonesia population. The next one is Sundanese with 15% share.
Besides these two major ethnics, the population of other ethnics are under 1% of population.
Composition of Indonesia Ethnics (15 Largest)
Inter ethnics marriage
Nowadays, a marriage done by people coming from different ethnics have become common. The situation has quite changed compared to 30-40 years ago. The cultureal boundary seems to has been gradually eliminated and loosened up.
It’s not unusual to see a man from Javanese ethnic marry a girl from Minangkabau or even Dayak. Many other cases of inter ethnics marriage can be found.