From what I understand, virtually all archaeologists and historians who study the matter agree that the Iroquois confederacy--the bringing together into political and religious union the Mohawk, Oneida, Onondaga, Cayuga, and Seneca peoples--was carried out as a result of the work of the Great Peacemaker and his disciple, Hiawatha. There is, as best I can tell, little dispute about their existence, even though the earliest written accounts come from at least three centuries after their life. That should be instructive to mythicists regarding how actual historians approach their subject matter, but of greater interest to me are the chronological debates around when the confederacy was founded. As I understand things, there are basically two major positions. One dates the founding of the confederacy to the mid-12th century, one to the mid-15th. The basis for these dates is primarily a Seneca myth that says that the last war among the Iroquois was brought to an end when the sky darkened, which the Seneca took as a sign that they should join the confederacy, thus bringing about the Great Peace (i.e. the founding of the confederacy). There are candidates for this eclipse in 1142 and 1451. The arguments then move to which date can best be supported on the archaeological data from what is today New York and Pennsylvania, where the Iroquois resided.
Aside from being interesting in its own right, this again drives home how comparatively easy we have it in early Christian studies. Our chronological debates regarding events tend to focus upon ranges of a few years. Did Paul flee from Damascus in 36 or 37, as Campbell argues? Or 33 or 34, as I'm inclined to think? These debates are important. They have consequences for what we do with other aspects of early Christian chronology, and chronology will remain always the backbone of history. But they are nothing compared to "Was the Iroquois confederacy founded in 1142 or 1451?" We wrangle over three years, Iroquois specialists debate over three centuries. We should celebrate the richness of the data at our disposal, and the fact that the debate over such crucial events as the flight from Damascus can be narrowed down to such a small range.