A few known facts:
The tribe of Levi was not allowed to be counted:
"But the Levites were not numbered among them by their fathers’ tribe;
for the LORD had spoken to Moses, saying:
Only the tribe of Levi you shall not number, nor take a census of them among the children of Israel" — Numbers 1:47–49.
The tribe of Levi was not assigned any land of its own.
Instead, the Levites were spread throughout the lands of the other tribes and providing the religious structure of the country, with Aaron's descendants as priests.
Joseph's two sons, Ephraim and Manasseh, were adopted by Jacob (Israel), forming two half-tribes in place of the tribe of Joseph: "And now your two sons, Ephraim and Manasseh, who were born to you in the land of Egypt before I came to you in Egypt, are mine; as Reuben and Simeon, they shall be mine." — Genesis 48:5.
The birthright promises were inherited by Ephraim and Manasseh, and they retained the family name Israel.
The messianic promises were inherited by Judah, and passed through King David and his descendants.
When Israel split into two kingdoms, the tribe of Benjamin remained with, and eventually became assimilated into, the tribe of Judah, who are also known as Jews.
Even during Jesus's time, some people still identified themselves as being Benjaminites.
Paul for instance, in Phillippians 3:5, described himself as "of the stock of Israel, of the tribe of Benjamin, a Hebrew of the Hebrews; concerning the law, a Pharisee".
The Kingdom of Israel was taken into captivity by the Assyrians.
The Kingdom of Judah (including Benjamin) was later taken into captivity by the Babylonians.
Eventually though, they returned to their homeland, centered around Jerusalem.
They are the ancestors of modern Jews.
Today, those named Cohen are considered descendants of the Levitical priesthood (Y-chromosomal Aaron - Wikipedia).
In the first century, historian Josephus recorded that "the ten tribes are beyond the Euphrates till now, and are an immense multitude and not to be estimated in numbers".
Since then, those ten tribes of Israel have been lost to mainstream history, but there is much speculation about what happened to them.
One theory is that they were taken by the Assyrians who migrated from the Black Sea area into what is now central Germany.
From there the tribes continued on, settling Scandinavia, the British Isles, and northwestern Europe.
Many Danes believe themselves descendants of the tribe of Dan.
Scots have significant Persian genes, and traditionally avoid certain non-kosher foods, such as eels and pork.
Some people (including Queen Victoria herself) believe that the current British throne is the continuation of the line of David.
It's a fascinating subject, especially for students of prophecy, but not an essential part of Christianity itself.