Darn bach yn Linesandsplines sy’n sôn am orthograffi ieithoedd brodorol America:

If I remember right, many writing systems were imposed on tribes by European missionaries, mostly in the nineteenth century. Bringhurst said that the mid-1800s were the heyday for devising new alphabets (novel sets of symbols, not new fonts) and so the Native American languages provided many opportunities for this sort of stuff.