Proto-Hakka (also called Common Neo-Hakka, CNH) is the reconstructed proto-language from which all Hakka varieties descend.
Like all branches of the Sinitic language family, proto-Hakka is difficult to reconstruct through the comparative method due to its multistratal lexicon.
Later large migration waves due to the An-Shi Chaos and the fall of the Northern Song dynasty to the Jurchen-led Jin dynasty led to large increases of population, and conflicts between the migrants and pre-existing Highlanders of Sinitic ethnicity.
This implies that Neo-Hakka is the sister branch to She Chinese, forming a bifurcating tree from their common ancestor.
The finals reconstrcted violate phonotactic rules expected from the Mainstream Hakka dialects, such as forbidding velar codas after front vowels.
For example, the Dark Level tone is realized as [˦] (44) in Moiyan (Meixian),[12] whereas in Ngiaupin (Raoping) it is [˩] (11) and in Ningdu it is [˦˨] (42) or [˦˧] (43).