Historically Judaism has been represented by the mountain Jews. Movses Kalankatvasi refers the arrival of mountain Jews in the Caucasus to the 1st century B.C, while researchers have different view upon this issue.
According to one source, mountain Jews which are the most ancient Jewish communities generate from the people of Israel, driven away from Palestine by the shahs of Assyria and Babylon and settled in Midia. Their ancestors were the first to establish Judaism and resided apart from Palestine and did not participate in the persecutions of Jesus Christ in the beginning of their formation as a single community. In Media they formed mixed communities with tats. Thus, mountain Jews spoke the language of tats, which is the dialect comprising Perian arami and Hewish words.
Other researched consider that mountain Jews were moved to the East Caucasus by Sasani ruler Khosrov Anushirevan the first (531-574). The ruler built towers in the Caucasus and settled Persians and Jews, removed from Mesopotamia to these cities. The tat language spoken by mountain Jews also survived since that period.
At least it is known that mountain Jews came to Azerbaijan fifteen centuries ago as a result of the policy of Sasanies, were settled in the borderline districts for ensuring the security of the country, and though being in close relations with local inhabitants they preserved their religion, traditions, life style and the way of thinking.