Minecraft wiki entry for Things_not_to_do, associated text: In Java Edition, if the player is in a village at midnight, there is a 10% chance that a Zombie siege could begin. Dozens of zombies spawn regardless of how well-lit or walled-off the village is. A few good sieges can easily wipe out the player's local village, and it is extremely tedious to try to repopulate it with zombie villagers. Staying out of the village boundary is sufficient to prevent zombie sieges from occurring, but it is still advised to stay farther away from the village, in order to prevent random zombie spawns.