Yeisu Kasu, the Era of Happiness, is the name for a society founded in Nama by Kava, although its people had adopted the language that later became Babakiam rather than their ancestral language which had developed from Subumpamese. Their nation was also known as Nipanu-Malamuppa.
The phonology of the proto-language, Yeisu Kasu, as spoken from 3138 AD to 3302 AD was, for consonants:
Labials: /p ṗ b m f β w/ Dentals: /þ/ Alveolars: /t d n s z/ Postalveolars: /č ǯ ž/ Palatals: /j/ Velars: /k ḳ ġ ŋ h g/ Pharyngeals: /ħ ʕ/
Voiced stops had an odd distribution, occuring almost entirely in word-initial position. Word-internally, the contrast was not between voiced and voiceless stops but between single and double voiceless ones. These two contrasts were not related to each other, but loans from Babakiam into CV languages often treated the single voiceless stops as voiced stops in intervocalic position.
There may have also been a marginal /š/ and /x/.
And for vowels:
/a i u ā ī ū ə/
The language still retained its tones, and in fact was more tonal than even Khulls since it had created new contrasts in primordial closed syllables by changing them into open syllables.