Answer: There is no official or regulatory definition of the term "ancient grains". Usually when marketing companies use this term on packaging they are referring to grains like einkorn, teff and spelt, farro, and sorghum. The idea marketers are trying to portray is that these grains are older than wheat and this makes them somehow better - but in fact wheat has been domesticated (grown specifically for cooking or baking purposes) for over 12,000 years. The reason that wheat has been grown and bred so extensively around the world is because of the versatility of the grain.
For individuals with celiac disease the key is to avoid gluten containing grains. Just because a product is labeled "ancient grains" does not necessarily mean that grain is gluten-free. For example, einkorn, spelt and farro all contain gluten and would not be safe for someone with celiac disease to consume.
Bottom Line: If you enjoy the different taste or texture of products that contain "ancient grains" that's great - but this doesn't necessarily mean they are more nutritious or safe for someone with celiac disease.
On history of bread: http://www.historyofbread.com/bread-history/history-of-wheat/
On celiac disease and "ancient grains" - https://www.beyondceliac.org/gluten-free-diet/is-it-gluten-free/ancient-grains/
Leah McGrath, RDN, LDN
Ingles Markets Corporate Dietitian