Corned beef comes from the brisket and silverside (just under the topside) of the cow. Both of these are tough cuts requiring either long, slow cooking, or pickling in brine, or both — hence their use in corned beef.See this article for lots more background on corned beef, including the oldest historical info.hat part of the cow does corned beef come from. March 16, 2006 Diane Duane 1 Comment. We’ve had about (EDITED, 17 Mar 2011) twenty three hundred queries about this today. We always get these this time of year, and more of them every year that goes by.