I learned that Tomahawks are purely a European invention. Introduced by our favorite pedo John Smith of Pocahontas fame from his embellished and romanticized stories of the native population. It's only associated with American Indians because it was one of the most common traded goods to them. Mostly because of the iron being superior to the stone and bronze tools they had. Also, the "unique" designs of the different areas attributed to them are from the different markets. i.e. the spaniards, french, etc.
The design of a small axe head was preferred over the household axes the colonist had for being too unwieldy for their purposes. Basic smithing and at times the axes weren't even properly heat treated. It was only after the Indians started to trade for iron ore that they still kept the boarding axe design but, made the more elaborate styles.