User blog comment:FairyRaven/Fairy Tail Chapter 465: 400 Years, Review and Commentary/@comment-71.222.52.171-20151210023306/@comment-4829046-20151211110217

True, but I believe Mashima is going for a fusion of Western and Japanese God themes, much like he does with other elements in the series. Ankhseram as well as Mildian Magic Academy that Zeref belonged to seem to be closer to Greek/Egyptian while the Yakuma clan, hence Minerva's magic, seem closer to Japanese or some other oriental deities. I am not refuting the anon in that they might be completely separate due to this, but it's still speculation at this point.