Thanks for the question, Mihaita. You are asking about Zechariah 9:9:
Rejoice greatly, O daughter of Zion! Shout aloud, O daughter of Jerusalem! Lo, your king comes to you; triumphant and victorious is he, humble and riding on an ass, on a colt the foal of an ass.
This passage in the Old Testament is one of the "messianic scriptures" used as blueprints to create the mythical messiah, as at Matthew 21:5:
"Tell the daughter of Zion, Behold, your king is coming to you, humble, and mounted on an ass, and on a colt, the foal of an ass."
It's quite obvious the writers of the gospel story simply took passages from the Old Testament to create their fictional character, based on what they believed Jews were expecting and would accept.
Moreover, the motif of the savior riding the ass(es) is a mythical one and can be found in the story of Dionysus
I've written a bit about this motif in my book The Christ Conspiracy
. Astrotheologically speaking, the motif represents the sun "riding the little asses" in the constellation of Cancer.
You can read more about the similarities between Dionysus and Jesus in my books and in this article:Dionysus: Born of a Virgin on December 25th
Why suffer from Egyptoparallelophobia, when you can read Christ in Egypt
? Try it - you'll like it: