linguistic:voice_change, structural:scholar_edition
Written evidence

Yiddish orthography developed towards the end of the high medieval period. It is first recorded in 1272, with the oldest surviving literary document in Yiddish, a blessing found in the Worms machzor (a Hebrew prayer book).

This brief rhyme is decoratively embedded in an otherwise purely Hebrew text. Nonetheless, it indicates that the Yiddish of that day was a more or less regular Middle High German written in the Hebrew alphabet into which Hebrew words – מַחֲזוֹר, makhazor (prayerbook for the High Holy Days) and בֵּיתֿ הַכְּנֶסֶתֿ, 'synagogue' (read in Yiddish as beis hakneses) – had been included. The niqqud appears as though it might have been added by a second scribe, in which case it may need to be dated separately and may not be indicative of the pronunciation of the rhyme at the time of its initial annotation.

Over the course of the 14th and 15th centuries, songs and poems in Yiddish, and macaronic pieces in Hebrew and German, began to appear. These were collected in the late 15th century by Menahem ben Naphtali Oldendorf. During the same period, a tradition seems to have emerged of the Jewish community's adapting its own versions of German secular literature. The earliest Yiddish epic poem of this sort is the Dukus Horant, which survives in the famous Cambridge Codex T.-S.10.K.22. This 14th-century manuscript was discovered in the Cairo Geniza in 1896, and also contains a collection of narrative poems on themes from the Hebrew Bible and the Haggadah.