Rosh — Rabbeinu Asher הרא"ש — רבינו אשר
who carried the Ashkenazi tradition into Spain, author of a halakhic digest of the Talmud
Rabbeinu Asher ben Yechiel grew up in Germany, in the world of the Tosafists, and was the leading student of the Maharam of Rothenburg. When his teacher was imprisoned and forbade his own ransom so as not to encourage extortion, leadership of German Jewry passed to the Rosh. As persecution worsened he fled around 5063 to Spain, and the community of Toledo received him as its head.
Something rare then happened: the two great traditions — Ashkenazi, grown from Tosafist argument, and Sephardi, grown from the codes of the Rif and Rambam — met in one man. The Rosh wrote the «Piskei HaRosh», a halakhic digest following the order of the Talmud, presenting both schools and deciding the law. His responsa, covering commerce, family and communal life, became a model.
His importance is visible in the outcome: when Rabbi Yosef Karo compiled the Beit Yosef and the Shulchan Aruch, he ruled by the majority of three — Rif, Rambam and Rosh.
His son Rabbi Yaakov wrote the «Arba'ah Turim». The Rosh died in Toledo in 5088.