Classical Dwarven language

The Classical Dwarven language - also known as Classical Dwarven Koiné - was a variant of Dwarven language, or rather, a stage during the evolution of the Dwarven Koiné. It was the lingua franca / koiné of the Dwarven region while it was a spoken language (between 1000 BEKE and 100 AEKE) - its spoken form eventually evolved into the contemporary koiné, while its written form merged into and influenced Temple Dwarven.

Evolution from Old Dwarven
The earliest step in the evolution was the voiced stops developing post-vocalic allophones. This was followed by the voiceless stops becoming voiced in the same postvocalic environments, except before other voiceless stops (including the glottal stop), where they became voiceless fricatives instead.

The above-described consonant shift was purely allophonic (thus neither phonemicized nor lexicalized) until complete removal of the schwa, which made the new non-sibilant fricatives phonemic. The voiced fricatives would be devoiced word-initially in clusters with voiceless stops, such as  →  →.

The aforementioned schwa-removal and word-initial progressivevoicing assimilation in consonant clusters also led to the creation of a whole new class of phonemic affricates. When this coalesence happened word-medially, it produced geminated affricates.

However, most of these only appeared in their simple, ungeminated forms word-initially, usually appearing only in geminated forms word-medially. Many of them were unstable and would be either deaffricated or simplified into stops later on.

Simultaneously with the aforementioned consonant shift, the vowels had their respective allophones consolidated as  after slender consonants,  after broad consonants. After the removal of the glottal stop and the palatal approximant  (which happened after the aforementioend consonant shifts), these allophones truly became phonemic, although still with the constraint of only being allowed to appear either word-initially or after their respective class of consonants.

Consonants
With some exceptions - namely the opposition of the broad versus the slender  - the difference between the broad and slender consonants wasn't the articulation of the consonant itself (such as a palatal or velar offglide), but the colouring on the vowels, with historical  being pronounced as  after broad consonants and  after slender consonants respectively.

Many of these consonants weren't particularly stable and were noted to be prone to being shifted in pronounciation in casual speech very early on. The voiced dorsal affricates were particularly unstable, and thus were the first to deaffricate  (when not geminated) very early on, and simplify to stops  when geminated. This was followed by all the other non-sibillant affricates following suit and deaffricating, thus merging with their fricative counterparts. When geminated, they became simple stops instead. The sibilant affricates were not deaffricated, presumably because their fricative counterparts already appeared word-initially.

Vowels
Unlike its consonant system, the vowel system of Classical Dwarven was very much stable and remained virtually unchanged for an entire millenium. Or, at the very least, the precisely number of contrastive vowels never changed, only their exact articulations shifted gradually.

The language also had one diphthong:.

The vowels in yellow - - could only appear after slender consonants (or word-initially), due to their historical origins as allophones of  after slender consonants.

The vowels in grey - - could only appear after broad consonants (or word-initially), due to their historical origins as allophones of  after broad consonants.