Walloon in Walloon Brabant means that it is in the Wallon part of the former province of Brabant of Belgium. Brabant was an old region, the Duchy of Brabant. The word Brabant appears for the first time in the seventh century when the abbey of Nivelles was founded in the pagus Bracbatensis (pagus is a Latin word meaning a very small town, with only few houses).
Walloon Brabant is the youngest and the smallest province of Belgium. The province was created in 1995 when the former province of Brabant was split along the language border in three parts: a Flemish part (Flemish Brabant), a Wallon part (Walloon Brabant) and the Brussels Capital Region, which no longer belongs to any province.