רבנו אשר – ר’ אשר בן יחיאל – רא”ש – R. Asher b. Yechiel – Rabbenu Asher – c. 1250-1327 – Primarily known for his responsa, Rosh was already an acknowledged leader of German Jewry when he fled persecution, settling in Toledo, Castile (in present-day Spain). The Rosh’s immigration from Ashkenaz to Sefarad was impactful in bringing knowledge and methods of learning from the latter to the former, especially the work of the Tosafot.
The Rosh himself was the descendant of Chasidei Ashkenaz, an important 12th-13th century pietistic movement. While in Ashkenaz, Rosh lived in Cologne, as well as elsewhere in the Rhineland, notably Worms, and probably Tzarfat, northern France. He studied under Maharam of Rothenberg, eventually fleeing after his teacher’s imprisonment and the Rindfleisch massacres of 1298, anti-Jewish riots that swept through Germany in that year. In 1303 he began his journey, apparently with his family, to Sefarad, via Italy and Provence.
Rosh settled in Toledo, where his son, the Tur (R. Ya’akov b. Asher), continued his Ashkenazi-Sefardi legacy, becoming famed as Ba’al ha-Turim, the author of the code of law Arba’ah Turim. Rosh is known for writing a code of Talmudic rulings, modeled after the Rif’s, called Piskei ha-Rosh or Hilkhot ha-Rosh. He is also noted as an author of voluminous responsa and of the ethical work Hanhaggot ha-Rosh (also called Orchot Chayyim)1, which was later much studied in the Lithuanian Musar movement of the 19th-20th centuries. In addition to these, some lost or unpublished, are the Rosh’s commentaries and Tosafot (to which he added the teachings of his teacher, Maharam).