Rome's Defeat

In 321 BC,Rome was invaded by the Celts (Senones).Only Vesta's watch geese saved the city.But what if the geese hadn't warned Rome?

Point of Divergence
The Celts take Rome because the geese don't warn the Romans.Then,they march to Veii,where the Roman Republicans had fled to.They then conquer that city.Although the Celts eventually withdraw,history will never be the same.

Effects

 * Verginetorix forms a united Celtic Empire.
 * Parthia and Egypt are very powerful.
 * Christianity was not centered in Rome but in Alexandria/Persepolis.
 * The Crusades happen early.