Buttermilk is what was left over after having made butter. Either sweet or sour cream was used to make butter. We used to let some milk sit in a crock for a couple of days, unrefrigerated. The cream would settle on top. This cream was skimmed off and accumulated until enough was collected to make butter. It takes about a quart of cream to make about a pound of butter. Buttermilk was considered an excellent drink and also used in many ways in cooking. The butter when separated from the buttermilk would be washed several times and then normally salted and packed into a form for use.