Why did the spanish's named Mexico Mexico?

Answer 1

Originally the Spanish called Mexico "Viceroyalty of New Spain", with the capital being Mexico City, later when Mexico became independent it was renamed "United Mexican States", mainly derived from Mexico City (former Mexico-Tenochtitlan, the capital of the Aztec empire).

At the time of independence there were other options for the new country's name, which was eager to assert a difference with its "Mother Country". Among these were América Mexicana (Mexican America) and Anahuac (name for the territories under the Aztec Empire's power or influence).

In fact Nicaragua, a country in Central America, derives its name from Anahuac, being Nic-Anahuac (To this point the Anahuac reached).