The first king of Saudi Arabia had apparently almost 100 kids with many wives and concubines, so I don't think it's unprecedented in some cultures (especially for the very powerful- think Henry VIII but gone mad).
I think the early Mormons (including founder Joseph Smith (who apparently had 28) and leading figure Brigham Young (who had 55)) had many wives. It is peculiar, and is not allowed and is viewed as abhorrent by many in Western society, hence the modern Mormon church bans polygamy and excommunicates any member who practices it.
But I heard that after same sex marriage was allowed across the whole of the United States, one person wrote, 'If same-sex marriage is allowed, why not multiple marriage?'. I think the reason for that is it ends up in some of family feud over wills and rivalries between spouses of the same person.