Two-tiered Relexification in Yiddish

by the 15th century, the descendants of the Judaized Khazars also relexified their Kiev-Polessian (northern Ukrainian and southern Belarusian) speech to Yiddish and German, Yiddish thus uses a mixed West-East Slavic grammar and suggests that converted Khazars were a major component in the Ashkenazic ethnogenesis.