haggis often regarded as the national dish and exclusive property of Scotland, is the archetype of a group of dishes which have an ancient history and a wide distribution. All of them are relatively large parcels of offal mixed with cereal and enclosed in some suitable wrapping from an animal’s entrails, usually the stomach.
The concept of haggis is based on preservation. When an animal was slaughtered, the perishable offal had to be eaten at once or preserved in some way. Salted, packed into a stomach, and boiled, its keeping time was extended to a couple of weeks. Similar considerations produced blood puddings, some of which include offal as well as blood.