The Bavarian purity laws defined beer in that part of the world as something that can only have hops, water and wheat.
Hops, water and barley. I think not using wheat was kind of the point actually, since wheat can be made into bread, and you wouldn’t want a bread shortage, would you? Banning others from brewing wheat beers, and then giving a monopoly to your own court brewery to corner the market, is also a baller business move.
But that’s fine, embrace the end! Rome was a slave society with incredible wealth disparity. They massacred people for entertainment. They conscripted guys for like 20 years to plunder and collect taxes that went mostly to the very top, the richest of families. Good riddance.