I remember having Golden Hammer and Dwarven Dark, both dwarven brews. I don't know who came up with those names but they have a good kick. The rest is just a blur...
Everyone knows that dwarves are the best brewers.

Beer (whether ale or lager), in theory, could be made from any type of grain. It wouldn't neccessarily have to be barley, wheat, rye, or any other grain specific to the real world, just some sort of 'grainy' plant. I would assume that in Yliakum beer is made from the same grains as the breads since the processes to make both are nearly the same. They both require yeast (or maybe Yliakum just has some other bacteria similar to yeast). The main differences are that the grain is ground up into flour for bread while only cracked and soaked in water for beer and bread is a heck of a lot thicker.

Hops is somewhat optional and used for bitterness, aroma, and as a natural preservative. Again, Yliakum could just have a leafy plant with properties similar to what we know of as hops. This same leafy plant could also be used for tea. Who knows. We may have walked right past a patch of this plant while taking a stroll in the hills and just not recognized it for what it is.