For thousands of years of Jewish history in the Levant, in the land between the Jordan River and the Mediterranean Sea, the people who lived and governed that land were Jews, who spoke the Hebrew language and who practiced the Jewish religion.
There are three buckets of independent evidence that prove this. I like to call them:
1. Rocks in the ground —archeological evidence.
2. Words on the page—documentary evidence.
3. Blood in the veins—DNA evidence.
In the law, one piece of evidence is good, two pieces of evidence is great, but when three fully independent pieces of evidence corroborate one another, when they didn't get together and get their stories straight, but they still confirm what one another is saying, that's dispositive proof.