Zollverein, the Customs Union.
Literally, it means an alliance formed by members to eliminate trade barriers between them, creating a tightly knit trade and contingency region, but in reality, the situation was not so straightforward.
Just as the renowned economist Friedrich List proposed establishing the "German Customs Union" to eliminate Austrian influence over the German states, leading them towards the "Lesser Germany unification plan" dominated by Prussia; a certain democratic Lighthouse Country proposed the TTP and TTIP to exclude a certain rabbit; Li Lin's proposal of a customs union also had the intention of eliminating the suzerain's influence, and even went a step further, by achieving substantial division economically while leaving room for maneuver at the political level. Finally, there was the intention of forcing Charlemagne to make the first move and thereby lose the moral high ground.