Larish (1999) establishes the two languages as forming two distinct subgroups of a larger Moken–Moklen branch.
[1] Moken and Moklen are linguistically and culturally related but distinct from each other, with Moken speakers primarily being sea-based hunter-gatherers, while Moklen speakers are land-based people living in villages and towns of southern Thailand (Larish 2005).
Moken has a very wide distribution, while Moklen is exclusively spoken on the western coast of southern Thailand.
[4] Larish (1999)[4] classifies the two languages Moken and Moklen as part of a larger Moklenic–Acehnese-Chamic-Malayic ("MACM") subgroup.
In a recent classification of the western Malayo-Polynesian languages, Smith (2017: 459)[6] argues based on phonological evidence that Moklenic is a primary branch from Proto-Malayo-Polynesian.