After the American Revolution there was much turmoil between the Americans and the Iroquois. The Iroquois were gradually moved west as expansion occurred, some tribes went north to Canada. The Iroquois tribes were divided amongst themselves and many were destroyed by their own in fighting.
They were affected like many other Indian tribes. First, they were devastated by wars. Their confederacy was broken up some by different nations taking different sides in the American Revolution. Then, after the Revolution, they were attacked by the Americans (for having taken the British side). That pretty much destroyed their nation and drove them off their lands.