I would think that ancient cities of refuge did have walls. They weren't there to defend wealth but the lives of refugees from those who sought avengement. Babylon was the first known city of refuge established for the god Marduk-Ra after he was found guilty in the murder of Dumuzi-Osiris. Later, Hammurabi fled to this same place after putting out the eyes of a fellow prince. And it was Hammurabi (a.k.a. Moses I) who is credited with establishing/mandating cities of refuge for Israel.
Surely there were and still are very many dialects of Arabic. Hebrew also evolved over time, and this was one of the most effective means of proving the recently "surfaced" Josiah tablet to be a fraud. The tablet's creator intended to have Josiah say, "I made repairs to the temple." In the language of Josiah's day the phrase would have been read as "I made damages to the temple"!!
Hebrew was a dead language for a very long time, which is what prevented it from changing further.
© Charles N. Pope, US Library of Congress. All rights reserved.