The earliest recipe from ancient Rome lists pomegranate seeds, pine nuts, and raisins that were mixed into barley mash.
In the Middle Ages, honey, spices, and preserved fruits were added.

Fruitcakes soon proliferated all over Europe.
Recipes varied greatly in different countries throughout the ages, depending on the available ingredients as well as (in some instances) church regulations forbidding the use of butter, regarding the observance of fast.
Pope Innocent VIII (1432–1492) finally granted the use of butter, in a written permission known as the ‘Butter Letter' or Butterbrief in 1490, giving permission to Saxony to use milk and butter in the Stollen fruitcakes.

Starting in the 16th century, sugar from the American Colonies (and the discovery that high concentrations of sugar could preserve fruits) created an excess of candied fruit, thus making fruitcakes more affordable and popular.
The earliest recipe from ancient Rome lists pomegranate seeds, pine nuts, and raisins that were mixed into barley mash. In the Middle Ages, honey, spices, and preserved fruits were added.
Fruitcakes soon proliferated all over Europe. Recipes varied greatly in different countries throughout the ages, depending on the available ingredients as well as (in some instances) church regulations forbidding the use of butter, regarding the observance of fast. Pope Innocent VIII (1432–1492) finally granted the use of butter, in a written permission known as the ‘Butter Letter' or Butterbrief in 1490, giving permission to Saxony to use milk and butter in the Stollen fruitcakes. 
Starting in the 16th century, sugar from the American Colonies (and the discovery that high concentrations of sugar could preserve fruits) created an excess of candied fruit, thus making fruitcakes more affordable and popular.
Fruitcake