Tungusic languages
There are some proposed sound correspondences for Tungusic languages. For example, Norman (1977) supports a Proto-Tungusic "*t" &gt; Manchu "s" when followed by "*j" in the same stem, with any exceptions arising from loanwords. Some linguists believe there are connections between the vowel harmony of Proto-Tungusic and some of the neighboring non-Tungusic languages. For example, there are proposals for an areal or genetic correspondence between the vowel harmonies of Proto-Korean, Proto-Mongolian, and Proto-Tungusic based on an original RTR harmony. This is one of several competing proposals, and on the other hand, some reconstruct Proto-Tungusic without RTR harmony.