Having slept well on this idea of combining story-ideas, I must now marshall all the good reasons why this is not a good plan. I walked away from the Salt Road because Slovakia and environs are a long way away and I don't read Slovak or Polish or any other relevant Slavic language beyond a rudimentary level. So a really deep historical novel would stretch my resources, as well as take a very long time to write.
What's different in switching settings from a Dazhiikewin in the norther Prairies/Wilderness to, say, the ground between Nitra and Krakow? The caveat remains that there are limits to the depth of the history I could access, though I must admit that probably sufficient material is available in English to create a credible post-petroleum (EU) world. Let's imagine, for the sake of argument, that the new site is Nitrawa, which is located on the shore of the Great Hungarian Sea (to the south), by the raging Nitra River, backed up against the mountains between Nitra and Novy Sacz (capitol of the Krakow region). Between are the Romii. There is a desire to open the old salt road between the two (a passage from commerce and communication).
Nitra (capital of Moravia) is part of the New Union (of city-states), as if Novy Sacz (capitol of Galicia). The rest of the general eco-history might remain. This is a post-petroleum world, something like 100 years in the future (though this is negotiable, depending on the status of artifacts and the level of divergence I'd like to posit. This could all happen at the end of The Age of Rain, precipitated by a combination of carbon-based warming and volcanic eruption. This would have caused famine and population decrease/mobility -- the succeeding age, without carbon pollution and with sun and adequate rain would be one characterized by the possibilities of prosperity. The necessary commerce between north and south could indeed be driven by a need for salt, to cure the fish that came from the new Sea to ship further inland. In this setting, once could still have an urban setting (Nitra) and rural settings between there and Poland, as well as along the Vah and Dunajec.
So find out that it's not just the Salt Road, but also the Amber Road ... I'm sure there's some more history here. The amber road went from the Baltic to the Adriatic, but with the mining of salt in southern Poland from the 14th century, the same road would have used the Dunajec-Poprad-Vah passage, or so it seems to me. In any case, there's sufficient historical record here for my uses.] The thing is ... I'm fascinated by salt.