The original homeland of the Iroquois was in upstate New York between the Adirondack Mountains and Niagara Falls.  Through constant migration, they gained control of most of the northeastern United States and eastern Canada.  At its maximum in 1680, their empire extended west from the north shore of Chesapeake Bay through Kentucky to the junction of the Ohio and Mississippi Rivers; then north following the Illinois River to the south end of Lake Michigan.

During the hundred years preceding the American Revolution, wars with French allied Algonquin and British colonial settlement forced them back within their original boundaries once again.  Their decision to side with the British during the Revolutionary War was a disaster for them.  In the United States, much of the Iroquois homeland was surrendered to New York land speculators in a series of treaties following the Revolutionary War.  

The Iroquois call themselves Haudenosaunee, meaning "people of the long house."  There are five sub-nations of Iroquois:  the Cayuga, the Mohawk, the Oneida, the Onondaga, and the Seneca.  

Very simply, the Iroquois were the most important native group in North American history.  Culturally, the women owned all property and determined kinship.  After marriage, a man moved into his wife's longhouse, and their children became members of her clan.  Iroquois villages were generally fortified and large.  The distinctive, communal longhouses of the different clans could be over 200 feet in length, and were built about a framework covered with elm bark.  

Agriculture provided most of the Iroquois diet.  Corn, beans, and squash were known as "deohako" or life supporters.  The women owned and tended the fields under the supervision of the clan mother.  Men usually left the village in the fall for the annual hunt and returned about midwinter.  Spring was fishing season.  Other than clearing fields and building villages, the primary occupation of the men was warfare.  Warriors wore their hair in a distinctive scalplock, although other styles became common later.  While the men carefully removed all facial and body hair, women wore theirs long.  Tattoos were common for both sexes.  Torture and ritual cannibalism were some of the ugly traits of the Iroquois, but these were shared with several other tribes east of the Mississippi.  The False Face society was an Iroquois healing group which utilized grotesque wooden masks to frighten the evil spirits believed to cause illness.

The Iroquois were farmers whose leaders were chosen by their women.  Founded to maintain peace and resolve disputes between its members, the Iroquois League's primary law was the Kainerekowa (the Great Law of Peace) which stated that Iroquois should not kill each other.  The League's massive adoptions also explains why it was so relentless in its pursuit of the remnants of defeated enemies.  

It was the Iroquois political system that made them unique, and because of it, they dominated the first 200 years of colonial history in both Canada and the United States.  There were never really that many of them.  And, the enemies they defeated in war were often twice their size.  Although much has been made of their Dutch firearms, the Iroquois prevailed because of their unity, sense of purpose, and superior political organization.  Since the Iroquois League was formed prior to any contact, it owed nothing to European influence.  Proper credit is seldom given, but the reverse was actually true.  Rather than learning political sophistication from Europeans, Europeans learned from the Iroquois, and the League, with its elaborate system of checks, balances, and supreme law.