Can region be defined outside of the theme's .info file?
Drupal 7 has 5 default regions: 


regions[sidebar_first] = Left sidebar
regions[sidebar_second] = Right
sidebar
regions[content] = Content
regions[header] = Header
regions[footer] = Footer
regions[highlighted] = Highlighted
regions[help] = Help


Regions aren't inherited by parent themes: https://drupal.org/node/225125. 

If I'm not mistaken you used to be able to define regions in theme_region(), but I believe that's no longer being used.