The much-mooted hypothesis, original with Ramstedt (1912) and later refined by Poppe (1960), to the effect that a number of Altaic etymological sets in which certain Mongol intervocalic velars appear to correspond directly to Turkic intervocalic labials are to be explained in historical-phonological terms by postulating the earlier existence in the original language of a suprasegmental conditioning factor, probably a movable feature of pitch, is reinvestigated in the light of the Middle Korean written records; these texts preserve overt evidence for the inheritance of this same conditioning factor in their lexically significant tonic accent notations.