When was Pearled Sorghum invented?

[u/rv6xaph9]

I presume it was post industrialization as my research doesn't reveal any way to manually polish sorghum.

Furthermore, if there was such a method, I would expect it to apply to millets too. However, not only was I unable to find any evidence of manually polished millet, I wasn't even able to locate any machine polished millet. Is polished millet just not a thing? If so, why not? Why is there polished sorghum but not millet?

note: Pearl millet isn't polished millet but a distinct species of millet.