That's what I thought too.
I think the 'origin of udon' might depend on the school of (religious) thought you subscribe to. ^_−☆
Shingon-shu: Kukai brings udon to Shikoku in the Heian period (806).
Rinzai-shu: Enni brings udon to Fukuoka in the Ninji-era. (1241).
As I'm addicted to Kotaro's sanuki udon (Hayashi-san is a Kagawa native), and am careful not to bite the hand that feeds me, I'm going with the Kukai/Kagawa story.
Whichever is the original, you'd better like your udon really soft and kind of mushy, like most of the folks in Fukuoka. Kyushu style udon is known for being very soft, friendly for the old folks. I've seen TV shows showcasing Fukuoka style udon and how it's boiled to perfection for about an hour. Udon in the Chugoku region of SW Honshu is similarly soft, probably thinner, but not as mushy as Fukuoka style. The really toothsome, chewy stuff that most people like is Sanuki style from Shikoku.