If everyone in Yantai knows about Longkou fans, I won't say it. In terms of favorable conditions for sweet potato growth, Shandong has a unique climate and geographical (specifically geological) advantages, so Shandong is not only the main producing area of sweet potato in China, but also the main producing area of sweet potato starch, sweet potato vermicelli and vermicelli! It can be said that almost every region in Shandong has one or several vermicelli factories.

In Shandong, except Longkou, vermicelli and vermicelli are produced on a large scale in other areas, such as Liangshan County and surabaya county (catkin group) in Jining, Pingyin County in Jinan, Shan County and Dingtao County in Heze, Linshu County and Tancheng County in Linyi.

By the way, most of today's vermicelli and vermicelli are made by machines, and they are rarely made by hand. I don't know if what you said "mainly machinery" is the same concept as what I understand.

Incidentally, those vermicelli manufacturers who shouted at the top of their lungs the slogan "Solemnly declare, fake pure sweet potato vermicelli, vermicelli" actually have a considerable amount of corn starch or even cassava starch mixed in their products (not only in Shandong, but also in some manufacturers in Hebei, Henan, Shanxi, Shaanxi, Hunan, Sichuan, Chongqing and other places, and some simply use corn starch and cassava starch to produce so-called pure sweet potatoes. If you need pure sweet potato vermicelli and vermicelli, you'd better go to a reputable manufacturer!

I hope my answer will be of practical help to you.