en_tn_condensed/luk/11/44.md

unmarked graves

"graves without makers." Graves were ceremonially unclean because of the dead bodies in them. An unmarked grave did not have a mark to warn people that it was a grave and that there was a dead body there.

that people walk over without knowing it

If someone walked over a grave, he would become ceremonially unclean because the grave was unclean. Alternate translation: "that people walk over without knowing that it is a grave" or "that people walk over without knowing that is is unclean"