Complex sentence: The Mohawk are one of the Six Nations of the Iroquois League; at the time of the American Revolutionary War, they lived primarily in the Mohawk River valley in what is now upstate New York.
Split into simpler sentences: The Mohawk are one of the Six Nations of the Iroquois League. At the time of the American Revolutionary War, they lived primarily in the Mohawk River valley in what is now upstate New York.