For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
There are several proofs about the life of Christ in general and the people he encountered. Here are few examples
a)Pilate Stone
http://en.wikipedia.org/wiki/Pilate_Stone
it is limestone which was used as is put by Pilate in the building he opened in honour of Tiberius Caesar Augustus. It has the following inscription
To the Divine Augusti [this] Tiberieum...Pontius Pilate...prefect of Judea...has dedicated [this]
b) Flavius Josephus
The writings of the 1st-century Romano-Jewish historian Flavius Josephus include references to Jesus and the origins of Christianity. Josephus' Antiquities of the Jews, written around 93–94 AD, includes two references to the biblical Jesus Christ in Books 18 and 20 and a reference to John the Baptist in Book 18.
c)Almost all modern scholars consider his baptism and crucifixion to be historical facts
[Jesus Remembered by James D. G. Dunn 2003 ISBN 0-8028-3931-2 page 339 states of baptism and crucifixion that these "two facts in the life of Jesus command almost universal assent"]