There is no such specialty as beef noodles in Anhui, but there are noodles. The origin of noodles is indeed in Anhui, but it is only in a small area called Taihe County. The locals eat "mutton noodles" instead of "beef noodles".
Probably because Anhui people from Taihe County came to North China with mutton noodles, they found that northerners prefer beef noodles, so the opposite technology was improved to meet the tastes of local people. After mutton soup was changed into beef soup, it just met the taste of northerners, so it became popular. It is estimated that Anhui people didn't expect this bowl of noodles to be a mess in Hebei.