Did Ghengis Khan exist? How do we know? Documentation.
There are a couple of old documents written by a Roman historian named Flavius Josephus. He was not a Christian and was only concerened with recording the history of Israel. Both of these speak of Jesus. Not sure of both do but one most definately speaks of Jesus' murder.
Here you go.
Originally posted by Flavius Josephus
" About this time there lived Jesus, a wise man, if indeed one ought to call him a man. For he was one who performed surprising deeds and was a teacher of such people as accept the truth gladly. He won over many Jews and many of the Greeks. He was the Messiah. And when, upon the accusation of the principal men among us, Pilate had condemned him to a cross, those who had first come to love him did not cease. He appeared to them spending a third day restored to life, for the prophets of God had foretold these things and a thousand other marvels about him. And the tribe of the Christians, so called after him, has still to this day not disappeared. " - Jewish Antiquities, 18.3.3 §63
Here is a quote by the Roman historian Tacitus. Here he speaks about Nero blaming the Christians for a fire that had destroyed Rome in 64A.D.
Originally posted by Tacitus
Nero fastened the guilt . . . on a class hated for their abominations, called Christians by the populace. Christus, from whom the name had its origin, suffered the extreme penalty during the reign of Tiberius at the hands of . . . Pontius Pilatus, and a most mischievous superstition, thus checked for the moment, again broke out not only in Judaea, the first source of the evil, but even in Rome...
From the Bablonian Talmud:
Originally posted in the Talmud
On the eve of the Passover Yeshu was hanged. For forty days before the execution took place, a herald . . . cried, "He is going forth to be stoned because he has practiced sorcery and enticed Israel to apostasy."
To discuss his diety, sanity or motive is one thing but it is an absolute rediculous notion to suggest that he did not exist. This one man has changed the history of the world. So much so that we number the days by him.