Complex sentence: Aztlán (from,) is the mythical ancestral home of the Nahua peoples, one of the main cultural groups in Mesoamerica and, by extension, is the mythical homeland of the Uto-Aztecan peoples.
Split into simpler sentences: Aztlán (from,) is the mythical ancestral home of the Nahua peoples, one of the main cultural groups in Mesoamerica. And, by extension, is the mythical homeland of the Uto-Aztecan peoples.