The main sources of our knowledge regarding Nazareth, its history and the important passages of the Gospel about the time Jesus spent there, are first of all the neo-testamentary texts themselves, second the numerous other accounts left to us by pilgrims in the course of the past centuries, third the local Tradition, which give precisions or add nuances, and last archaeological excavations, begun as early as the nineteenth century, which confirm the texts of the New Testament.
Today the excavations continue in Nazareth. There is an international effort to bring to light the still hidden history of the Holy Land, and those different teams are decades away from exhausting the pool of archeological sites laden with vestiges yet to be revealed.
On a wider scale, our familiarity with the Hebrew nation, of their Old Covenant with God (Old Testament) to their New Covenant (New Testament) sealed by the person of the Messiah, Jesus Christ, Mary's son, true God and true man, comes to us as well, although more indirectly, by a small handful of ancient non-Christian historians (a Jew named Flavius Josephus and a few Romans: Pliny, Tacitus, Suetonius).
A crucial discovery happened on the shores of the Dead Sea
We are referring to the famous discoveries in Qumran in 1947. On the northwest bank of the Dead Sea, in the ruins of an Essenian monastery from the 2nd century, some scrolls were discovered. They are now known as the "Dead Sea Scrolls" and they contain parts of all the books of the Bible (except the Book of Esther), and the entire book of Isaiah (an Old Testament prophet who lived in the sixth century A.D.)...
A person familiar with the Book of Isaiah, which announced the Incarnation and the maternity of the Virgin (Is 7:10-14) centuries before the Annunciation, can surely weigh impact these archeological discoveries have made both in the fields of historical research and biblical studies.
The accuracy of the biblical texts, especially the translations in Greek and Aramean, is proven by all the documents found in Qumran dating from the 1st century A.D. (There have been no discoveries of remains from the Herodian period.) These documents show, granted some minute variations, basically the same text that we can find in our bookshops today!
Some ancient Jewish books (the Talmud for example) allude to Christ and his disciples, as do the traditional Eastern collections that are contemporary to the Talmud.