In Indonesia, the language is called “bahasa Indonesia” (the language of Indonesia). The word bahasa (language) is written in small letters as it is not part of the name of the language. It is hence wrong to refer to the language as “Bahasa Indonesian”, or, even worse, “Bahasa”. Not only because it is odd to refer to Indonesian as “language”, but also because the same term “Bahasa” is used by many expatriates in Malaysia for the Malay language.
The Indonesian language received its modern name in the first half of the 20st century. Before, the language was known as “bahasa Melayu” (Malay). At a youth congress of the national movement that aimed for independency from the Dutch colonialists in 1928 it was proclaimed that the Malay language should from now on be called “bahasa Indonesia”. But is was only after the Dutch had to leave the archipelago in 1942 when the new name became official.
The name Malay was mentioned for the first time by the Chinese monk I Ching (634–713) who studied Buddhism in Sumatra. The name is also mentioned in several stone inscriptions in Sumatra, which can be considered the homeland of the Malay people.
The Malay language has many dialects, such as Jakarta Malay, Jambi Malay, Kelantan Malay, Kupang Malay, Papuan Malay, Terengganu Malay etc. Two Malay dialects have gained prominence as national languages: Malaysian, which is the national language of Malaysia, Brunei-Darussalam, and Singapore, and Indonesian, the national language of Indonesia.
All those languages are closely related to each other. In other words they are all dialects of Malay. This does not mean that they are all mutually intelligible. A speaker of Kupang Malay will have difficulties understanding a speaker of Kelantan Malay, and a speaker of Jakarta Indonesian will not readily understand a Malaysian from Kuala Lumpur who is speaking colloquial Kuala Lumpur Malay.
Can we hence conclude that bahasa Malaysia and bahasa Indonesian are mutually unintelligible? The answer is a clear no! Indonesians who listen to a television programme in formal Malaysian will perfectly understand the content of the programme, and they will also be able to read books written in Malay without any difficulty.
Here you can learn more about Indonesian Malay: