The version that I have heard the most locates it on the West coast of Mexico, within the state of Nayarit. I also know of the thesis that proposes that Cerro de Culiacán, a mountain in the state of Guanajuato, is the legendary place. Finally, I've been told that the chicano movement has tried to place Aztlan far up to the north, inside the current day states of California, Arizona and New Mexico.
Huh, I have not heard of Nayarit as being one of the choices for Aztlan. That's interesting because during the Epiclassic period Jalisco and surrounding areas like Nayarit experienced an influx of different cultural traditions that has been attributed to migrations from the Bajio that was in the grip of a long-term and severe drought.
At the site of Alta Vista several ceramic vessels were recovered. These vessels are unique in two regards. The first is that they are pseudo-cloisonné. Pseudo-cloisonné vessels are unique due to the way they are made. A potter takes a previously fired vessel, possibly an old vessel and possibly a freshly made one, and applies a thin cap of clay, usually grey, to the entire vessel. The potter then cuts out a design from the clay to create cells. The potter then presses into these cells differed colored pigment compounds with each cell being one color. When the design is complete the whole thing remains unfired and thus the design is extremely fragile and prone to decay. This is technique is definitely not a native method to the region and was either learned from others or migrants brought the technique with them.
The second interesting thing is that at Alta Vista several of these vessels depict the eagle eating a snake motif people usually associate with the Mexica. This does not mean that these people were Mexica, but they may have been a related group leaving their homeland due to drought. And because of the early time period, they were most likely earlier migrants such as the Toltec. My guess is these people left their drought stricken land to continue to farm rather than convert to hunting and gathering and trying to continue to subsist in their native area. It was only when the drought became worse that later Chichimec (hunting and gathering) groups left because they could no longer sustain themselves.
And if ceramics doesn't convince you, West Mexico doesn't begin using prismatic blades until this introduction by other people, people who probably did not have abundant sources of obsidian and thus used this technique to conserve their obsidian. Jalisco is one of the richest areas for obsidian and there was not much of a need to make prismatic blades.
To throw in some linguistics, the most commonly spoken languages at the time of conquest were Uto-Aztecan such as Caxcan. Huichol and Cora are Uto-Aztecan, but had branched out much earlier than Nahuatl or Caxcan and may have been in the area longer than Caxcan. I've translated some town names in the area that still have their Caxcan or other dialect name. Some of them are a hit and some of them are a miss due to differences in nouns and even verbs that do not show up in any Nahuatl dictionary.
Published drawings:
http://i.imgur.com/QXFAJ1M.jpg
http://i.imgur.com/wFex11v.jpg
http://i.imgur.com/MZv4Iij.jpg
Photographed vessels:
http://i.imgur.com/RVaR17z.jpg
http://i.imgur.com/sK5H8in.png
Beekman, Christopher S. and Alexander F. Christensen
2003 Controlling for Doubt and Uncertainty Through Multiple Lines of Evidence: A New Look at the Mesoamerican Nahua Migrations. Journal of Archaeological Method and Theory 10(2):111-154.
Beekman, Christopher S.
[1995 The El Grillo Complex of Central Jalisco: Teotihuacan Expansion or Epiclassic Movements From the Northern Frontier. Paper presented at the 60th Annual Meeting of the Society for American Archaeology, Minneapolis.] (https://www.academia.edu/400456/The_El_Grillo_Complex_of_Central_Jalisco_Teotihuacan_Expansion_or_Epiclassic_Movements_From_the_Northern_Frontier)
[2012 El Grillo and Epilogue. The Reestablishment of Community and Identity in Far Western Mexico. Paper presented at the 77th Annual Meeting of the Society for American Archaeology, Memphis.] (https://www.academia.edu/5000266/El_Grillo_and_Epilogue._The_Reestablishment_of_Community_and_Identity_in_Far_Western_Mexico)
2012 Disruption Before and Behind: Causes and Consequences of Migration in Epiclassic Northern Mesoamerica. Presented at the workshop "Disruptions as a Cause and Consequence of Migration in Human History".
