Complex sentence: Many of the Iroguois tribes in western New York, including the the Seneca, Cayuga, Onondaga, Oneida, Mohawk and Tuscarora, disliked the colonists encroaching into their territory, which roughly comprised the Allegheny, Genesee, Upper Susquehanna and Chemung River basins.
Split into simpler sentences: Many of the Iroguois tribes in western New York, including the the Seneca, Cayuga, Onondaga, Oneida, Mohawk and Tuscarora. They disliked the colonists encroaching into their territory, roughly comprising the Allegheny, Genesee, Upper Susquehanna and Chemung River basins.