“We begin with Palm Sunday. Two processions entered Jerusalem at the beginning of the week of Passover, a tinderbox time in the city, with the Jewish people celebrating divine deliverance from the past Egyptian Empire while under the present Roman Empire. Two very large and very lethal riots took place precisely at Passover in the generations before and after (the year) 30 CE.
Jesus entered the city from the east in another procession, a counterprocession. Whereas Pilate rode into the city on a war horse, Jesus entered on a donkey. Mark makes it clear that Jesus planned it in advance: he tells his disciples to go into a village to get a donkey and says, ‘If anyone says to you, Why are you doing this? just say this, the Lord needs it and will send it back here immediately.’
Implicitly in Mark 11:1-11 and explicitely in Matthew 21:4-5, the symbolism makes use of Zechariah 9:9-10, which speaks of a king of peace on a donkey who will banish the war horse and the battle bow from the land.
The contrast is clear: Jesus versus Pilate, the non-violence of the kingdom of God versus the violence of empire. Two arrivals, two entrances, two processions — and our Christian Lent is about repentance for being in the wrong one and preparation to abandon it for its alternative.” (”Collision Course,” Marcus Borg and John Dominic Crossan, “The Christian Century,” March 20, 2007)