Basement.
The wall of corpses was not intended to block anything, but was created deliberately.
There was only one purpose.
To create the atmosphere of an 'underground graveyard' with this type of corpse wall.
Increase the total amount of Yin Qi in the underground area, fostering a better environment for pathogenic fungi and facilitating the cultivation of ghouls.
Not just the place where Han Dong and others lived.
The basements of other buildings also have similar structures, but one has to dig a bit deeper to discover the structure of the underground passages.
The passage to Han Dong's dwelling only involved a wall.
Besides, the scent of contamination in the basement passages was intense; ordinary people wouldn't know where they led, and without enough information, no team would rashly venture deeper.
Han Dong came alone to the basement.
Re-opening the originally sealed wall exposed a passage overflowing with the scent of contamination.