I'm going to "link" this question to something in this week's parsha (Torah reading):
וַיַּצֵּ֧ב יַעֲקֹ֛ב מַצֵּבָ֖ה עַל־קְבֻרָתָ֑הּ הִ֛וא מַצֶּ֥בֶת קְבֻֽרַת־רָחֵ֖ל עַד־הַיּֽוֹם׃
And Jacob set up a pillar upon her grave; It is the pillar of Rachel’s grave unto this day.
The Torah does not state that there was any inscription on the pillar. I assume that it was just a pile of stones arranged in a some shape so that people passing by would recognize that there was a grave there.
AT what point did it become common to engrave tombstones? Was / is it done for strictly personal reasons or are there halachot or minhagim that indicated that tombstones must or should be engraved rather than just leaving a pile of stones?