It's a bit of guesswork, but the Greek region of Boeotia comes to mind. According to the German Wikipedia page for Boiotien, the adjective "böotisch" was used derogatory to mean something like uneducated, untaught, coarse, uncouth, boorish.
In der griechischen Antike bedeutete (vor allem bei den Athenern) „boiotisch“ so viel wie "ländlich grob, ungebildet"; die Griechen nannten die Boiotier bisweilen gar "boiotische Schweine". Mit dieser Wortbedeutung ging "böotisch" auch in die gehobene deutsche Sprache des 18. und 19. Jahrhunderts ein, etwa bei Lion Feuchtwanger, der die Figur Paul Hessreiter in seinem Roman Erfolg von der "Böotisierung" Münchens sprechen lässt.
Translation by me:
In ancient Greece, "boeotian" (especially used by Athenians) meant "rural uncouth, uneducated"; the Greek sometimes even called the Boeotians "boeotian pigs". With this meaning, "boeotien" found its way into the elevated German language of the 18. and 19. century, for example with Lion Feuchtwanger, who lets the character of Paul Hessreiter in his novel "Erfolg" speak about the "boeotification of Munic".
(I basically made up "boeotian" as well as "boeotification", because I can't find an existing or established version)
It would stand to reason to assume that "Böotentum" is from the same context. Judging by the quoted examples, it clearly seems to be derogatory, at least.