Sourdough has been made since ancient times; it dates back to Ancient Egypt around 1500 BC
. In Europe it has been used as the main kind of bread until they developed a way to cultivate yeast in the Middle Ages. Rye bread is still popular in Europe and since baker's yeast isn't really useful for leavening rye bread the sourdough method is still used. Sourdough also has a history in the US, during the California Gold Rush it was used as the main kind of bread because it was more reliable than other kinds of bread and could last for longer periods of time. One of the most famous breads in the US is the San Francisco sourdough which is very popular to this very day. It has been made for over 150 years and has become popular due to its fine taste with seafoods and soups alike. Today sourdough isn't very popular, it takes too long to make but some restaurants keep it on their menus. There are many kinds of sourdough but most are made the same way, one exception is the Amish Friendship Bread which isn't sour due to the presence of milk and sugar in the recipe. While sourdough isn't the most efficient way to make bread and maybe it doesn't have the best taste in the world, it has something unique to it and shows the way nature works, it doesn't rush anything it doesn't try to do more than it can, yet everything gets done when it should be done.