Super Beginnings, how young superheros came to be.
An indeterminate time period sometime between 1000 B.C. and 500 A.D.
Focuses on cultures and trade routes within this time in a general unidentifiable way. More of an overview than history lesson.
No permission needed to play in this universe as long as you don't involve my characters.
(Unless your story doesn't cement the time frame any closer than I have indicated, and my characters remain unaltered. As in cameo appearance only.)
Romans o.k. If no identifiable personages date them.