We've got many historian types here, some actual history teachers!
Everything, even my fantasy work is heavily, historically influenced. I like all kinds of history, every culture really. However, my recent efforts is developing a distinctly feudal Japanese setting, intended for publication - soon.
Although something I always wanted to do (develop a Japan-based setting.) My February Map Challenge entry, and my previous months efforts creating a Ukiyo-e Japanese wood block print styled map symbols in January, helped boost my recent efforts for publication.
Ukiyo-e Map Objects thread
Gempei War Map thread
As I said, any culture's history is fascinating to me.