The "Rema" (Moses Isserles) started writing his commentary on the Arba'ah Turim, Darkhei Moshe, at about the same time as Yosef Karo. Karo finished his work "Bet Yosef" first, and it was first presented to the Rema as a gift from one of his students. Upon receiving the gift, the Rema could not understand how he had spent so many years unaware of Karo's efforts. After looking through the Bet Yosef, the Rema realized that Karo had mainly relied upon Sephardic poskim.