I found this dungeon to be very difficult for my group of Mid game geared characters with stats 50+. Spider Factory: Spider Factory is home of the Spider Foreman who is the 'boss' of this dungeon and uses the Meitou Staff. For this reason I recommend you make sure your stats are higher than the enemies. You'll want to make sure your characters can handle multiple fights and recover well enough to handle a boss and his minions. Keep in mind that in many of these zones we're going to be fighting numerous groups of enemies and then sometimes a boss too at the various dungeons throughout the world.
Toughness is usually the best stat to compare to the enemies - having equal to or better Toughness is preferred. Since there are no levels in this game the only way we can gauge our strength against an opponents is to compare our stats.
If the zone requires you to have at least 10 characters with stats 50+ to survive there then it's most likely on this page. This page contains a list of all the zones in Kenshi that I would consider to be endgame zones.
Endgame Zones Loot Guides & Map Locations - Kenshi