Or Zarua

Rav Yitzchak the son of Moshe (Riaz) was born in Bohemia in 1180, but attained his fame in Vienna, where he lived until his death in 1250. His work was a halachic guide arranged according to the Talmudic tractates, and was very popular among Ashkenazic Jewry. He studied under many people, including Raavyah and the author of the Rokeiach, and he was among the teachers of Maharam MiRutenberg.