Judeo-German
From the late 13th century, there is evidence of the beginnings of the Yiddish language, which in the early phase is a variety of Middle High German, not distinct enough even to be described as a dialect, but written in Hebrew characters. In its early phase, it is normally referred to as Judeo-German; from the 15th century it becomes Old Yiddish. Poems in this idiom belong equally to the fields of Medieval German Studies and Jewish/Yiddish studies.
Notable works include the 14th-century Dukus Horant (a narrative poem known as the "Jewish Kudrun") or the 15th-century Bovo Bukh, the most popular chivalric romance in the Yiddish language.
Read more about this topic: Medieval German Literature