According to the Encyclopædia Iranica, "All Lori dialects closely resemble standard Persian and probably developed from a stage of Persian similar to that represented in Early New Persian texts written in Perso-Arabic script. The sole typical Lori feature not known in early New Persian or derivable from it is the inchoative marker (see below), though even this is found in Judeo-Persian texts". The Bakhtiāri dialect may be transitional between Kurdish and Persian. However, there was never a common ancestor to Luri. There are two distinct languages, Greater Lors (Lor-e bozorg), a.k.a. Southern Luri (including Bakhtiari dialect), and Lesser Lors (Lor-e kuček), a.k.a. Northern Luri.
^Don Stillo, "Isfahan-Provincial Dialetcs" in Encyclopædia Iranica. Excerpt: "While the modern SWI languages, for instance, Persian, Lori-Baḵtiāri and others, are derived directly from Old Persian through Middle Persian/Pahlavi".