The cultivators who resided in a such a large Middle Age ruin were definitely incredible. They would at least have been at the Divine Illusionary Realm. They could even have been Path Integration Realm beings.
Hence, after the members of the Petrification Cult discovered this place, they became extremely excited. Once they break through all of the defensive stratagems here, they could head straight into the ruins and find all the treasures within it. The ancient martial art practitioners of the Ming Palace were not as important right now. The members of the Petrification Cult could just kill them when they came across them and be done with the issue.