Dead Can Dance, RakimThe Language is a mixture of glossolalia and English.Glossolalia (from Greek glossa γλῶσσα "tongue, language" and λαλεῖν "to talk") is the vocalizing of fluent speech-like but unintelligible utterances, often as part of religious practice. Its use (including use in this article) sometimes also embraces Xenoglossy - speaking in a natural language that was previously unknown to and that is not understood by the speaker.
Look up Glossolalia in Wiktionary, the free dictionary.
While occurrences of glossolalia are widespread and well documented, there is considerable discussion within religious communities (principally Christian) and elsewhere as to both its status (the extent to which glossolalic utterances can be considered to form language), and its source (whether glossolalia is a natural, supernatural, or spiritual phenomenon).
https://en.wikipedia.org/wiki/Glossalalia