Israel was the northern Kingdom formed in 933 BCE in the north when King Solomon died. It was from here that the 10 tribes lived. The Assyrians had attacked in 721-715 BCE and had taken most of them captive. Then the Assyrian kings, Tiglath-Pileser III (732 BCE) and Sargon (721 BCE) exiled the northern tribes of Israel to Assyria, Media and land adjacent to Aram-Naharaim. Some most likely remained in and around their homeland. Some of their descendants preserved their identity among the Jewish population and others were assimilated.
Some were absorbed by the last Judean exiles who in 597 BCE-586 BCE were deported to areas adjacent to the place of exile of the 10 Tribes such as to Media, Assyria and Mesopotamia. A large section of people of the southern kingdom, Judah,were also exiled by Nebuchadnezzar to Babylon in 586 BCE.
Many have claimed to be descendants of the 10 tribes. They’ve been said to be in the mountains of Africa by Eldad Ha-Dani. Benjamin of Tudela heard they were in Central Asia. David Reuveni said he was the brother of one of their rulers in Arabia. Antonio de Montezinos said he found them in South America.
One story connected them to the Japanese while others put them in Anglo-Saxon countries, like claiming England’s kings were descendants. The Pashtuns in Afghanistan claimed descendency. At least today we have dna to check out claims.
Originally there were 12 tribes. The sons of Jacob were Reuben, Simeon, Levi, Judah, Issachar, Zebulun, Joseph, Benjamin, Dan, Naphtali, Gad and Asher. Moses designated the tribe of Levi with a priestly office, and they got no land, but Moses wanted to keep the tribal number at 12, a sacred number, so divided Joseph’s tribe into Ephraim and Manasseh.
Under Joshua, who was elected to follow in Moses’s footsteps when he died, the tribes of Reuben, Gad and half the tribe of Manasseh received land in what became Transjordan. Naphtali and Asher were sent to the Sidonian frontier in the Galilee. Issachar and Zebulun were to live in the Valley of Jezreel area. Ephraim and the other half of Manasseh went to the mountains of Samaria. Benjamin was to their south and Judah further south. Dan was to be along the seacoast around Jaffa and Simeon was to live in the Negev.
The Danites were expelled from their original inheritance by the Amorites and moved to the sources of the Jordan River. The men of Simeon took more land than their allotment by seizing land in Seir and the land of the Amalekites.
Things were working under the Judges but Solomon created a differnet administrative division of the country. When he died, the country then split into two with the tribes of Judah, Simeon, and most of Benjamin making the southern Kingdom which was then called Judah.
Today with the birth of Israel, many people are claiming descent from the Lost 10 tribes.
Resource: New Standard Jewish Encyclopedia