This is a question that popped into my mind when I read Piggy's mention of a "thousand years" rule of the Levites: What's really a tribe here? How is kinship to a tribe inherited over time - matrilinearly, patrilinearly? How different were the tribes from one another, in terms of language (dialects perhaps), cult, customs, even genetic or phenotypic appearance?
Ancient Hebrews were patrilineal.
There are many differences between Israeli and Judean culture, but their kinship customs were pretty much the same.
If you recall, Judea was the realm of the Southern tribes, centered around the Dead Sea. It's not the best land, a lot of desert and mountains. For much of this time the Philistines occupy a good bit of the Mediterranean coast to the west. The Sinai is to the south, and then Egypt beyond that. Mesopotamia, who covets the Mediterranean lands no matter who rules Mesopotamia at the time, is to the east with the Edomites and Moabites and others in between.
Above them is Israel, the realm of the Northern tribes, centered around the Jordan River and the Sea of Galilee. This is fertile land, lots of rolling hills, tributaries to the Jordan, and seacoast too. To the north, Syria is what we might call a frenemy, depending on the politics at the time, and to the northwest, empires like the Assyrians had their eyes on the Mediterranean as well.
There were continual battles in this area, which connected Europe with Africa via the Mediterranean coast, involving all of the different groups and nations I've mentioned above, and many more, with shifting lines of occupation and influence, the rise and fall of powers, over centuries.
Various semitic groups, who shared similar languages and cultures, lived in this area around the 1200s BCE. They were settled in various small settlements and surrounding farmlands with vague and shifting tribal territories.
Men in any one village or town would get wives from neighboring villages that belonged to the same tribe, or a closely allied tribe. Children of those marriages were part of the father's tribe.
During the 1100s BCE a confederation of tribes rose to power in that region, eventually controlling a territory about the size of the island of Corsica along the southern coast of the western edge of the Mediterranean Sea, connecting Egypt and Africa beyond it to what is now Turkey and the rest of Europe.
But they did not hold well-defined territories in the way countries do today. There was simply no way to do that back then. To control a territory simply meant that you had a lot of settlements there and you were well armed and trained, but people from other tribes would have towns here and there in the same region. You either made agreements with them over the use of springs, grazing rights, and such, or you ran them out, or decided not to put up a fight and hope they didn't try for more territory.
The actual details of the relationships among these various tribes are largely lost to history. We can use archaeology (including the study of ancient literature), linguistics, and DNA-empowered genealogy to reconstruct them to some extent, but that effort is still in its infancy, I think.
To get an idea of what they looked like, you could explore the paleontology and anthropology. I really don't know anything about that, though.
As far as language, cult, and customs, they were very close, with notable differences that varied in all sorts of ways. What foods did they eat or not eat? What were the names of their gods and mythic characters? To what extent were they influenced by the cultures which bordered their territories?
Early Hebrew culture was Canaanite culture, "Ugaritic" culture. Discoveries in Ugarit, which thrived in the northern region of this area in the 1300s and 1200s BCE, have provided us with a lot of information about the lives and beliefs and stories of the people who lived around there.
The group that rose to power in the 1100s traced their origins back to a common ancestor, Abraham -- whom some groups later traced back to Mesopotamia, while others traced him back to what's now Syria.
But the thing is, genealogies at that time weren't fixed. If you made a pact with a neighboring tribe, well, your story changed so that it turns out you have a common ancestor. If you later got into a war with that tribe, the story changed again so that their ancestor was a child of incest, or was cursed by god, or committed some atrocity, or whatever.
And you'll see this in the various accounts preserved in the Biblical literature. The tribes themselves were fairly stable through patrilineal lines, but the Hebrew coalition shifted and changed, and the official story of lineage shifted and changed with it.
Was it conceivable that people could somehow claim to be Levites to justify some claim to power or whatever, and get away with it? Was there a lot or only a little intermarriage between the Hewbrew tribes?
So in effect, to what extent is it even valid to equivocate the Levites of 50 BCE with those of 850 BCE?
It would not have been possible to simply claim to be a Levite clan.
Levitical status was strictly inherited. And local people knew who these families were.
There were a lot of bennies (as well as responsibilities) that went along with being a Levitical priest (which is redundant for Levitical Yahwism). No one could slaughter a lamb or calf without bringing it to you to kill, and you got part of it.
So, for example, when all sacrifice was centralized at the Temple under Hezekiah, this meant that all the non-Zadokite priests (the Zadokites were the subclan of Aaronites who controlled the Temple worship in Jerusalem) now had no legal source of meat, because they could not themselves hold land.
So when we're talking about the political battles which so heavily influence this literature, we have to understand that these battles are bare-knuckle brutal.
As for their history, we know the Levites are firmly entrenched, and battling each other for power, in Hebrew society in the 800s BCE, when they wrote the Old Judean and Ephraimaic Torahs.
There is no serious reason to doubt that the two main factions of Levites -- Aaronids and Mushites -- reigned as co-priests in Jerusalem around 1000 BCE.
And if their epic histories are built around a core of actual history, they are the group which established the first law code for the confederation as well as the enduring line of high priests of Yahwism maybe sometime around 1200.
Before that, given what we know about them, it seems that they lived to the south and either actually lived in Egypt for a time or intermingled with the Egyptians while living in Sinai.