The languages are lexically very similar, and retain a common, albeit simplified, Austronesian syntactical basis.
Even in the areas where it was once well established as a lingua franca, the use of Hiri Motu has been declining in favour of Tok Pisin and English for many years.
[note 1] The term hiri is the name for the traditional trade voyages that created a culture and style of living for the Motu people.
The name Hiri Motu was conceptualised in the early 1970s during a conference held by the Department of Information and Extension Services.
The Motu people are native inhabitants of Papua New Guinea who live along the southern coastal line of their country.
Traditional Hiri voyages carried prized treasures to the people of the Gulf of Papua.
The "Papuan" dialect (also called "non-central") was more widely spoken and was, at least from about 1964, used as the standard for official publications.
They form a continuum from the original "pure" language, through the established creoles, to what some writers have suggested constitutes a form of "Hiri Motu–based pidgin" used as a contact language with people who had not fully acquired Hiri Motu, such as the Eleman and Koriki.
[3] In the Hiri Motu language, the distinction between "inclusive" and "exclusive" forms of 'we' is very important.
With it, the sentence reads: Inai mero ese boroma badana ia alaia (literally, 'This boy
The language has a history pre-dating European contact; it developed among members of the Hiri trade cycle (mainly in sago and clay pots) between the Motu people and their neighbours on the southeast coast of the island of New Guinea.
By the early 1960s, Hiri Motu was the lingua franca of a large part of the country.
Since the early 1970s, if not earlier, the use of Hiri Motu as a day-to-day lingua franca in its old "range" has been gradually declining in favour of English and Tok Pisin.