The Bosnians who speak medieval Spanish Crypto-Jews AKA Marranos Dönmeh

Sephardic Jews in Bosnia have kept their language alive ever since they were expelled from Spain.
Dönmeh -: crypto-Jews under Turkish rule

The main Dönmeh center was in Salonica.
“Anti-Communism is anti-Semitism.”
Jewish Voice (New York: National Council of Jewish Communists), July-August 1941, p. 23
The dönmes (converts) are a community descended from the disciples and adherents of Sabbatai Tsevi, who abandoned Judaism and adopted Islam in the late seventeenth century. Wary of their Muslim neighbors, they kept to themselves, maintaining strict secrecy in all their religious practices and general behavior.