How often did medieval commoners migrate from place to place? Like, say the North had developed booming textile and lumber industries and a commoner from a different kingdom wanted to move there for the work, how likely would it be they could do that?

we-are-rogue:

racefortheironthrone:

Scholars seem to disagree, with some saying that most people never traveled further than ten miles from their birthplace, and other people pointing to the popularity of pilgrimage and other examples of medieval migration.

What I would say is that because most migration tended to be local and regional rather than long-distance, it would be unlikely that you’d see commoners moving to the North from Dorne. Rather, I think you’d see a lot of internal migration by Northerners and external migration from the northern Riverlands and the Vale. 

By the time you get a textile industry, you’re in the Late Middle Ages, and commoners migrate for ALL sorts of reasons:

to escape from plague, to escape from war, to find a war and make a living by pillage, to become brigands and make a living by pillage (same difference…), to find a better landlord than the brutal cheapskate you’re stuck with, to find any landlord because the one you had kicked you out (“booming textile industry” means raising sheep replaces agriculture, but it’s also less labour-intensive, so suddenly thousands of people are left in the lurch with no
livelihood and no home), to get yourself to that big city you hear so much about where maybe there are jobs, or to wander with other wanderers from town to town.

In England (and other parts of Europe), the textile boom coincided with — and party caused — tremendous social upheaval. I’m not sure how you can insert it in Westeros and assume nothing else changes. And while it’s debatable how common migration was before
the Great Spring Sickness

the Black Death, after that point it becomes TOO common, and the law keeps trying to suppress it in a crescendo of brutality, and keeps failing. The wave was unstoppable.

Of course, if we limit our scope to migration which is legal and desirable, or at least tolerated by the status quo, then it was pretty minor. But… why should we? Escaped serfs, expelled tenants, wayward servants, broken levies, rogues and vagabonds, and undesirable minorities of all sorts, were all commoners. Of flesh and blood, just like everyone else. They should count.

Further reading:

• J.J. Jusserand, English wayfaring life in the middle ages. Excerpt: “Outlaws and escaped serfs in 14th century England”.
• Lisa J. Steele, Fief:
  A Look at Medieval Society from Its Lower Rungs. Except:
  “Travelers, Bandits, Mercenaries, and Foraging Parties”.
• Fernand Braudel, “The Great Imprisonment” (excerpt from A History of Civilizations)
• This Rogue, “No rest for the wicked: Anti-vagrancy laws in Tudor England, 1495-1604”, “Stealing back the commons”
• Frank Aydelotte, “Elizabethan rogues and vagabonds: Origins” (excerpt)

This is an excellent addition. My only caveat is that, in Westeros, we have to take into account the greater distances involved, hence why I think you’d see migration to textile centers in the North primarily happening within the North and secondarily from the northern Riverlands and Vale, with sharp fall-off thereafter.