Moa'ah is a unique demonic breed of creature which is commonly found in Southern American. It's commonly found on land which supported massive carnage. According to Castiel, it was very common to be found on The Civil War battlefields where both sides (Union and Confederate) spilled their blood on fierce battles, but they somehow wiped out to the point it was no longer detected, even by the angels. It's very presence on a land is a signal of Apocalypse. At some point, it was tied on Judas's Noose.