In the same year, while resident at the University of Washington, he wrote a pedagogical grammar of the Aymara language for Peace Corps volunteers.
In the aftermath of WW2, this was challenged by Max Weinreich who proposed that it arose as Romance- speaking Jews Germanized their mother tongue as they migrated further north and east, in the wake of Crusader massacres.
Throughout the 1970s and 1980s, Wexler also subscribed to the traditional view of Yiddish as a very Slavicized dialect of Middle High German, dating back to its formation around the 9–10th century, when Romance-speaking Jews settled in the Rhineland and Bavaria.
[9] In the 1980s, Alice Faber and Robert King proposed a Knaanic origin, in West Slavic dialects as spoken notably in the Czech lands, and also in the areas of Poland, Lusatia, and other Sorbian regions.
He hypothesizes this second relexification of Eastern Yiddish took place in the 15th century, at which time the descendants of the Khazars no longer spoke a Turkic language but rather a mixed Slavo-Turkic.
[16] Wexler's hypotheses are based on analyses of numerous Jewish languages and introduce creolization as a factor in the formation of many of them.
Other than linguistic analysis, he separates Jewish cultural areas into Judeo-Greek, Judeo-Romance, Judeo-Germanic,[a] Judeo-Turkic,[17] Judeo-Tat, Judaeo-Georgian, Judeo-Arabic and Judeo-Slavic.
[22] Wexler rejects the theory that the differences between Eastern and Western Yiddish were caused by the former's greater exposure to Slavic, instead viewing the two dialects as two largely separate languages.
[23] Considering the logical outcome of his linguistic hypotheses to be that Ashkenazi Jews are the descendants of Iranian, Turkic, and Slavic proselytes.
They claimed that the DNA has originated in Northeastern Turkey in four villages whose names were, they argued, derived from the word "Ashkenaz."
The authors argue that this is where a non-Germanic "pre-Yiddish" was developed as an undocumented language for trade and that with the Judaization of Slavs it acquired its alleged Slavic component.
"[32] In reply, Elhaik, Wexler et al., dismissed the Flegontov paper as marred by lack of knowledge of Jewish history and a failure to evaluate relexification.
In this monograph, running to well over 1,400 pages, Wexler discusses the origins and relations of almost 300 lexemes he considers part of the "Afro-Eurasian elements in Yiddish".