Rabbeinu Chanoch Ehrentrau was born in 1854 in Alt-Ofen (today a district of Budapest).  He began his learning under the Rav of the city, Rav Mordechai Amram Hirsch, who later would be his father-in-law. After his bar mitzvah, he went to learn under Rav Feivel Plaut in the city of Nagysurány (also known as Šurany or שוראן – today part of Slovakia). Three years later, he entered the illustrious yeshiva of Pressburg and studied under the Ksav Sofer. In 1886 he received the position as Rav of Munich, which he filled for the next forty years. There he became close friends with Rav Nosson Nata Rabinowitz, who had been staying in the city to work on the Munich Codex and publish his work Dikdukei Sofrim. When Rav Rabinowitz passed away suddenly, Rav Ehrentrau completed his work on Meseches Chullin. Rav Ehrentrau authored many seforim covering a wide range of topics. He passed away in 1927.