As this was a large migration it was seen as an invasion however the hypothesis is still not unanimously accepted. It is said that the Aryans were the original inhabitants of Central Asia. The Aryans brought religious traditions known as Vedas and practices with them. They were even the first people in India to know the use of iron and brought horses along them. In Sanskrit the term arya means "noble". The Aryans lived as horsemen and cattle herders, clearing patches in the forest and inhabiting small villages. After taking over the Harappan civilization, Aryans absorbed the remnants of the civilization and integrated their own culture into it and formed the Vedic culture. However there is very little information about this transition from the Harappan culture to Vedic culture. Some scholars argue that when the Aryans first spread into India they were a conquering people and later they eventually mixed with the indigenous Harappan culture. The Aryan's religion reflected in their culture as well. They used to worship storm gods and sky gods. "This warlike nature was preserved in the later Vedic religion (see the "Rig Veda"), where the god Indra was portrayed as a conquering deity who smashed cities and killed enemies" (Ferguson, Corri. "The Aryan Migrations." India and Southern Asia Chronology. ThenAgain, 26 October. 1998. Web. 15 June 2015) Moreover as the name says, the Aryans used to consider themselves as superiors to the people they conquered. .
Toltecs.
Sometime in the 7th century after the collapse of Teotihuacan, migrants from the north moved into the valley of Mexico and this is where Toltec civilization was flourished. The story of the Toltecs confirms the significance of migration across the community lines of Mesoamerica. They continued the Mesoamerican heritage left to them by the earlier Olmec, Teotihuacan and Maya. During the 9th century CE Tolteca- Chichimeca people migrated to Culhuacan in the Valley of Mexico from the deserts and Toltecs also had their roots from Culhuacan.