Here is what an angel told Daniel in Daniel 10 which would have been about 550 B.C..
Daniel 10:20 Then said he, Knowest thou wherefore I come unto thee? and now will I return to fight with the prince of Persia: and when I am gone forth, lo, the prince of Grecia shall come. [kjv]
και ειπεν ει οιδας ινα τι ηλθον προς σε και νυν επιστρεψω του πολεμησαι μετα αρχοντος περσων και εγω εξεπορευομην και ο αρχων των ελληνων ηρχετο [lxx]
10:21 But I will shew thee that which is noted in the scripture of truth: and there is none that holdeth with me in these things, but Michael your prince. [kjv]
The angel is fighting "
with" the prince of
Persia and then the prince of Greece shall come. Is the angel fighting for or against those powers? is it clear. Is the "
prince" the leader of those powers or the power behind those leaders?
It would appear that the angel could be traveling through time to take care of needed business, first with the prince of Persia, and, later, with the prince of
Greece.