Archaeologically, 900 years ago, central New York was home to what is known as the Owasco period. Generally Owasco spans from 1000 CE to 1300 CE, with some (proto-?) Owasco traits showing up at the Kipp Island site (just north of Cayuga Lake) by 625 CE.

The Owasco period is a transitional time, during which the culture of the Finger Lakes slowly shifts from that of Hopewellian Middle Woodland into what we associate with the Haudenosaunee at the time of European contact. The Three Sisters agricultural system coalesces at this time. Maize becomes an important crop at the beginning of the Owasco period (though, based on phytoliths, the adoption of maize in the region may go back to 650 CE, with incidental amounts of maize first appearing around 300 BCE). Beans show up at the end of this period. The houses go from being circular, single-family homes, to becoming increasingly-elongated ovals, to finally having their ends squared off to become the longhouses of the historic period.

More importantly, for the purposes of your question, around ~1200 CE, we start to see the nucleation of villages at defensible sites and the construction of palisades. We also see increased isolation separating localized regions within the Finger Lakes, evidenced by local pottery remains becoming increasingly homogeneous. This has been used as evidence both for and against warfare actually. On one hand, the argument goes, warfare discourages communities from sharing ideas and ceramic styles, resulting in each community developing its own specific style. On the other hand, during the period of historic wars, we see the opposite occur, with pottery becoming more diverse as captives from various areas all bring their own unique style as they are adopted into the community. Personally, I don't see these as mutually exclusive. The Beaver Wars in the latter half of the 1600s likely don't have direct parallels in the Pre-Columbian era in terms of scale and objectives. We're unlikely to see the complete dismantling of nations and mass adoptions as we do in the colonial era.

Admittedly, this is a fairly conservative summary of the Owasco period, largely following the work of William Richtie (see his Archaeology of New York State). John Hart has been leading a debate against Richtie's definition of the Owasco, pointing out that some Owasco traits (like maize agriculture) may predate the Owasco period while others (widespread nucleation of villages) may actually post-date Owasco. That last one would be immensely important to your question if it turns out to be true. Check out Hart and Brumbach's The Death of Owasco - Hart has an updated version in Current Research in New York Archaeology: AD 700–1300 called "The Death of Owasco - Redux* as well.