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 seems to indicate that Klingons valued the bodies of their dead at some point, in contradiction to a line from "Heart of Glory"; after death, the Klingon body is but an 'empty shell'. It should be noted that this idea was also seemingly contradicted by the practice of ak'voh. It might also be possible that only the only the remains of important individuals were preserved.