Mona Mir, TX
Here is a brief answer:
OT 23 THE BOOK OF ISAIAH
11:12 And he shall set up an ensign for the nations, and shall assemble the outcasts of Israel, and gather together the dispersed of Judah from the four corners of the earth.
MY HUMBLE RESEARCH: The lost tribes of Israel had migrated to Afghanistan and Kashmir, and in time, embraced Islam. Encyclopedia Americana, 'Lost Ten Tribes' vol XVII.
The House of Israel had divided into two clashing factions after Prophet Solomon's death in 928 BC. His mighty kingdom got split into a northern kingdom called Israel with its capital Samaria, and a southern kingdom called Judah with its capital Jerusalem.
The two tribes of Benjamin and Judah inhabited the southern kingdom whereas the remaining ten tribes lived in the northern kingdom.
Assyrians (the ancient West Asian Empire) invaded the Samarians and took them captive to their capital Nineveh in 721 BC. Since then, they have been so mysteriously scattered through history that they are still referred to as the lost tribes of Israel! Some surviving Samarians intermarried with the Assyrians, and their progeny has been called Samaritans. Only about 500 of the Samaritans are surviving in the present day Israel.
The other kingdom, Judah, based in Jerusalem was invaded and completely devastated by the king of Babylon, Nebuchadnezzar, in 586 BC. He destroyed Solomon's Temple and took the two tribes captive to Babylon.
King Cyrus the Great of Persia, after defeating Babylon in 538 BC, allowed the surviving 5% (about 50,000 out of a total of one million) Jews to gradually return to Jerusalem. This reverse exodus took place over a period of 140 years.
Sadducees and Pharisees were the two major Jewish sects during the times of Jesus Christ. The latter are the only surviving sect of Judaism today, although there has been further schism among them.