What country does sourdough bread originate from?

Sourdough refers to the process of making bread using the naturally occurring lactobacilli and yeasts. It is the way bread was made to rise for thousands of years. The process of leavening bread (getting it to rise) was independently discovered by different groups of people all over the world at various times. There is no specific origin which can be identified for bread (and all bread was sourdough bread a thousand years ago) but one could guess that the earliest domestication of grains in the Mediterranean region was followed within a few thousand years by bread.