This is a reference to the history of the Finnish war of independence in 1918 in a slightly complicated way. Literally the phrase means "via Ostrobothnia". Ostrobothnia is Pohjanmaa in Finnish, which again might be translated as "land of the north". Besides "north" pohja also means "bottom". As a preparation to the war of independence a few thousand supporters of the independence movement received military training in Germany. They became to be called jääkäri(“Jager”) and they infiltrated back to Finland via Ostrobothnia. After the war it became customary to propose a toast by asking: Mistä jääkärit tulivat? ("Where did the Jagers come from?"), and to this one was supposed to answer: Pohjanmaan kautta ("via Ostrobothnia") and then the glasses were emptied to the bottom. Over time, the question has become unnecessary.