Why Mexican Native Americans developed great Civilizations, but USA Native Ameri

Question:

Why Mexican Native Americans developed great Civilizations, but USA Native Americans were nomad & uncivilized?

There are only about 30 phonetic sounds in the Maya language so a purely phonetic alphabet could in theory be written with 30 signs. It was originally thought that Maya writing was purely logographic because of the many hundreds of different glyphs. After a long period of attempts to decipher the Maya glyphs, it was discovered that the system was logosyllabic and became increasingly phonetic over time. Maya writing uses a syllabary made up of glyphs rather than a pure alphabet and is a mixed system. Many of the glyphs are polyvalent and have two or more meanings (Id. at 621). Glyphs have been identified that correspond to verbs, nouns, adjectives,and particles (Id. at 628). Maya writing is structured around glyphs and glyph groups. The glyphs are pictures. Main signs are larger and more central in a group. Affixes are joined to the main sign and may be prefixes (left), superfixes (above), subfixes (below), and postfixes (right) depending upon their position.

Best Answer - Chosen by Asker: if the mexicans are so advanced, then why do they all come to the usa??