Trade requires discussion
I strongly lean toward the idea that Hellenist astrology derived decans (later called "faces")
in some way, from Egyptian sources,
and I also lean to the idea that Hellenist astrology also likely derived the concept of the houses
from Egyptian sources (linked to the Egyptian concept of the Duat, or "underworld")
However, what about a possibly Jaimini (Indian) influence on Manilius relative to his decans
-can we try to say that India derived its decanate-concept from Egypt?
Well, one thing: it is a FACT that there were considerable contacts in the VERY ancient times
between Egypt+Sumeria (Mesopotamia)+the Indus River Valley civilization+the "Dravidian" culture of South India:
there was extensive trade among these very ancient civilization (predating the time of the Greeks),
so perhaps there was also an exchange of IDEAS as well...
discussion leads to an exchange of IDEAS as well