Per Soter, two bodies are defined to share an orbital zone if their orbits cross a common radial distance from the primary, and their non resonant periods differ by less than an order of magnitude.

Well, the short answer is, the Japanese immigrants came over, and a bunch of the bakers introduced them including at least one in Los Angeles, and one here in San Francisco called Benkyo do, which is on the corner of Sutter and Buchanan.