The Western Mexico (Spanish: Occidente de México) is a region of United Mexican States formed by the states of Nayarit, Jalisco, Colima, and Michoacán, and including the Revillagigedo Islands, Marías Islands, and several smaller islands. The region extends from the coastal plain of the Pacific Ocean, the Sierra Madre Occidental, the Volcanic axis, the basin of Balsas River, the Sierra Madre del Sur and the southwest of the Mexican Plateau.
Early archaeologists who wrote about the Western Mexico pointed that this region was somehow connected with Mesoamerica; then, other researchers felt that the archeology of the western area belonged to the Mesoamerican studies, and finally the more recent authors argue that the area should be incorporated into a redefined Mesoamerica. There is very little information about early human occupation of the area, the earliest evidence is a camp established on the basis of a volcanic mountain in the Bay of Matanchén, Nayarit,which is a likely date from 2200 to 1730 b.c. Part of the area was under the dominion of the Purépecha Empire
The New Kingdom of Galicia (Spanish: Nuevo Reino de Galicia) was one of only two autonomous kingdoms in the Viceroyalty of New Spain. The conquest of territory was accomplished by Nuño de Guzmán and named as Conquista del Espíritu Santo de la Mayor España (English: Conquest of the Holy Spirit of Spain Mayor). However, queen Joanna of Castile (Joanna the Mad ), mother of Charles V, did not agree with the name given to the conquered territory, and by Royal Decree, on January 25, 1531, ordered to call the conquered territory as Reino de la Nueva Galicia and was founded a city named Santiago de Galicia de Compostela as capital city.