In a similar vein, at http://archaeology.about.com/od/aterms/a/Aztlan.htm?nl=1 the semi mythical homeland of the Aztecs, known as Aztlan, has been sought far and wide with the most common location somewhere in northern Mexico or the SW of the US. It too is associated with a date not too distant from the Black Death as in this article it says the Aztecs migrated in the central Valley of Mexico in the 12th or 13th centuries – a 100 years plus too early. Plague would not cause a migration of a large number of people – but a drought may have. Hence, this is the most common driver of the Aztec migration – on the basis that northern Mexico and the SW were much drier at that time.
The migration from Aztlan was in tradition at the command of the Aztec god Huitzilopochtli – and Aztlan is thought to mean something like 'the place of whiteness' which may further associate it with the gods rather than an earthly location (see M Smith, 'The Aztec Migration of the Nahuati Chronicle: Myth in history' in Ethnohistory volume 31:3 (1984). In Worlds in Collision, page 245, Velikovsky says of Huitzilopochtli, he was a destroyer associated with death, fire, and pestilence.