Local Enemy Bestiary Serpent Trench
From Tzen, head east a little to the northeastern corner of your mini-continent to find a bridge heading east to what resembles a snake, really - the opened mouth at the north end, and going to the tail at the southeast bit.
Anyway, when you leave the bridge, you can either go north or southeast to Nikeah or Mobliz, respectively. The former will continue along the plot for you, and you’ll end up going there anyways; the latter allows some extra EXP., Gil, and some Magicite. You can get to either one pretty easily. We’ll just start with Mobliz, since there’s no real going back from Nikeah.