It's the little facts inside a story that can make or break it. Please check your historical fiction for setting errors!
Think of all the blood spilled in war - if it were merely blood that was required, the lands that were battlefields should forever be waist deep in lush grasses and yielding four times the corn of others for all eternity. - Gwenhwyfar, by Mercedes Lackey, page 313
King Arthur was a legendary British leader who lived in the late 5th or early 6th centuries.
Corn, or "maize," was domesticated in MesoAmerica and brought to Europe after trade routes were established in the 15th or 16th centuries.