Where does a thin pasta called Soba come from?

Soba is the Japanese name for buckwheat. It usually refers to thin noodles made from buckwheat flour, or a combination of buckwheat and wheat flours (Nagano soba). They contrast to thick wheat noodles, called udon. Soba noodles are served either chilled with a dipping sauce, or in hot broth as a noodle soup. They contrast to thick wheat noodles, called udon.