According to Ethnologue, Indonesian is a relatively small language of only 23 million speakers whereas Malay is said to have 39 million speakers. Wikipedia, which relies on the data provided by Ethnologue, cautions us that “the definition of a single language is to some extent arbitrary”. For this reason, “some mutually intelligible idioms with separate national standards or self-identification have been listed together, including Hindi-Urdu; [and] Indonesian and Malay”.
According to Wikipedia, the number of native speakers of Malay (Malaysian-Indonesian) is 37 million. As Malay is the national language of Indonesia, Malaysia, and Brunei-Darussalam, it is spoken by a large number of people who on a day-to-day basis speak local languages. Some of the regional languages are huge. Javanese, for instance, has 85 million native speakers, and is the 12th most widely spoken language in the world. Madurese and Sundanese, the two other language spoken on the island of Java, add another 48 million people. Other regional languages (bahasa daerah) of Indonesia, aren’t small either, Minangkabau, Balinese, Musi, Banjarese, Acehnese, Batawi, Sasak, Toba, Mandailing, and Makassarese are some more languages having between 1 and 6 million speakers.
Virtually all speakers of regional languages do also speak Indonesian. In many cases, they speak it more frequently, and often also better than their native language as Indonesian is the preferred language of inter-ethnic communication. More than 90% of speakers of regional languages are literate. When they write, they will almost exclusively write in Indonesian, and the literature they read they is entirely in Indonesian. The last newspaper in Javanese language was published about 75 years ago. The regional languages have also been heavily influenced by Indonesian, mainly in lexicon, but often also in phonology, morphology, or syntax.
As Indonesian is the only language of instruction in Indonesia (besides a small number of so-called “international” schools where broken English is used as the medium of instruction), and as schooling is compulsory and enforced, all Indonesian have to learn Indoneisan at the latest by the age of seven. When we ask Indonesians who grew up speaking mainly their mother tongue in the first years of their lives before they picked up the national language in school whether they consider themselves “native speakers” of Indonesian, the language is almost always a clear “yes”.
But the scenario as described above, is becoming increasingly rare. Most Indonesians nowadays grow up in a bilingual setting, and are from infant age on exposed to at least some Indonesian before they attend primary school. Code-switching is becoming the norm, not only for adults, but also for children.
The term “native speaker” has, like the term “mother tongue” many different definitions. As Pokorn (2005:6)
has observed “The concept of “native speaker” is defined according to different criteria, and [...] there is no objective definition of the concept which would cover all potential native speakers and not even the majority of them.” According to any of the definitions presented by Pokorn, the assumption according to which there are only 37 million “native speakers” of Malay-Indonesian is untenable.
“A first language (also native language, mother tongue, arterial language, or L1) is the language(s) a person has learned from birth or within the critical period, or that a person speaks the best and so is often the basis for sociolinguistic identity. ” (Wikipedia)
Indonesian-Malay is spoken predominantly in Indonesia, Malaysia and Brunei. The population of Indonesia is 237 million; Malaysia’s population is 27.5 million, and that of Brunei is 0.4 million. Another 3 million native speakers live in the southernmost province of Thailand, and the number of native speakers in Singapore exceeds 500,000. These are 268 million people who are either native speakers, or who, with very few exceptions, have learned Indonesian-Malay at school and are –more or less– “native speakers”. It is either close to impossible (in Indonesia), or very hard (in Malaysia) to find an adult who is unable to speak Indonesian or Malay. The literacy rate of both countries is 92%. In Indonesia, all literates, automatically speak Indonesian, and the percentage of adult speakers of Indonesian is approximately 95-97%. In Malaysia, the number is lower as some older Chinese Malaysians are not very fluent in Malay. As a comparison, 96% of US Americans speak English. Those few people who do not speak Indonesian tend to live in the countryside of the island of Java. In other words, wherever you travel, you will most likely never encounter someone who does not speak Indonesian!
Even if we are very conservative and consider only two third of Malaysians and 85% of Indonesians as fluent speakers (either native, or near-native), there are still more than 215 million speakers of Malay-Indonesian. After Chinese (1300 million), English (508 million), Spanish (417 million), Arabic (280 million) and Russian (277 Million), Malay-Indonesian is the sixth most frequently spoken language in the world (the numbers above include second-language speakers).