Entering the stronghold alone would be a death wish.
The Zanj'ir slaughter outsiders on sight.
The only way to get in without being killed is to appear to be under the effects of a zoatroid.
Even then, the mind-shackled are put to work.
You must obey all commands, or they will know your mind is still your own.
Once the Zanj'ir believe you are mind-shackled, it should be easier to navigate their domain and uncover their secret.