The Klingon mummification glyph seen in the fourth movie was identified in the script as coming from the earliest part of the Zanxthkolt Dynasty. This dynasty was not mentioned in the movie.
The practice of mummification would seem to indicate that Klingons valued the bodies of their dead at some point, in contradiction to the episode "Heart of Glory"; where the Klingon body was considered a 'empty shell' immediately upon death. It should be noted that this idea was also seemingly contradicted by the practice of ak'voh. However like it 'ak'voh it could represent an ancient and antiquated position that is no longer commonly observed, it might also be possible that only the remains of certain important individuals were preserved.