OK. Then that whole long discussion of whether there is or isn’t evidence that people did behave any given way in the past is irrelevant; in which case I’m not sure why you were arguing that people did and didn’t behave in particular fashions, let alone over whether you’re not going to read a particular book, or any book at all, on the subject.
I do think that “a right to leave” should be a fundamental right. Failing to grant it means that nobody has a right to choose where they want to live; and I can’t think of much more fundamental than that, other than, as has been brought up in thread already, the right to bodily autonomy.
A major complication with the right to leave is that it doesn’t mean much if there’s no place to go. Providing all people with a guaranteed right to live where ever they feel like could mean that some places get massively overloaded (though that itself would make them less desirable, in a sort of market forces of the feet); but I think it’s currently more of an issue of a combination of governmental barriers and of every place on the planet already having some complicated set of governmental rules. The Mormons ran into this even a couple of hundred years ago: they couldn’t find anywhere to live that didn’t forbid polygamy, and when they tried simply moving Away the USA caught up to them.
I’m not defending Mormon-style polygamy; just pointing out an example. If everybody has an individual right to leave, then everybody would have had the right to leave the Mormons; especially if they knew of examples of places that didn’t work like that, and that they could go there.
So part of the right to leave, if it’s going to work, has to be a right to knowledge about other places; and a willingness of at least some of them to take others in, or else the availability of vacant land suitable to live upon.
I think a lot of rights are entangled like that. A right to property, of whatever sort (and there are a whole lot of different ways to have the right to use property of various sorts), is useless to somebody imprisoned or otherwise constrained in their bodily autonomy that they can’t use it. A right to total bodily autonomy is useless if there’s no right to at least have a fair chance to get food and shelter.
And I doubt there’s any society that grants or has granted any right without restriction – except maybe for the right to leave. Because pretty much any other right is going to, in some cases, impinge on other peoples’ rights in that same area. (Even the right to leave could impinge, say, on somebody else’s right for child support; though that at least isn’t in the same area.)