Irish soda bread's origins are deeply rooted in 19th-century Ireland, a time marked by economic hardship, particularly during the Great Famine. The introduction of baking soda to Ireland in the late 1830s was a game-changer in home baking. It provided a low-cost and accessible alternative to yeast, which was expensive and hard to come by. This shift was crucial as it allowed for the use of soft wheat flour, prevalent in Ireland but unsuitable for yeast-leavened bread. Traditionally made with just four ingredients - flour, baking soda, salt, and sour milk (or buttermilk) - Irish soda bread was a simple, economical solution for many Irish households.