Kindest Regards wil and Dondi!
With due respect considering I am not Jewish, my understanding is that there was a point in the Old Testament where the tribes were at war with one another, and the tribe of Dan came out on the losing end. Dan was ostracised and sent into exile. I have heard some claim they went on to become the Greek warriors we know as the Spartans. Others claim they went on to settle in Europe, and note various placenames that echo the name of Dan, such as the Danube river. These would rank among what the Romans called "barbarians" that gave them such fits for so long on their frontiers.
After Dan was exiled, the tribe of Joseph was split and the two half-tribes of Ephraim and Mannasseh were now counted as whole tribes. Levi indeed had no land inheritance, as their service to G-d became their inheritance. After the time of Solomon, the nation split into two camps, the Southern House of Judah comprised the tribes of Judah and the remnant of Benjamin, and Levi is also included (although it is reasonable to believe that some portion of Levi may have been spread out among the Northern House). The Northern House of Israel was composed of the remaining tribes, and these are those carried away captive by Assyria. It is here that the tribes became "lost," although there are various ideas put forth by different scholars as to where they went. Some believe they went over the Caucasus mountains and became what we know as "Caucasians." There are other tantalizing clues throughout European history, but nothing so far that any scholar is willing to stake their career on.
What we know today as the Jewish nation stems from the Southern tribes, and it is said that the priestly class of Cohenen (sp?) can trace their geneology back to the time of Solomon and before. I have seen a paper pointing to genetic information that seems to support this.
The miracle in my mind, is that the Jewish people were able to retain so much of their culture and genetic lineage in the diaspora. Everywhere they found themselves, they managed to fit in and yet stand apart.
I would be very interested to hear what our Jewish friends have to say to this matter.