Works.bepress.com/cgi/viewcontent.cgi?article=1029&context=michael_e_smith&sei-redir=1&referer=http%3A%2F%2Fscholar.google.com%2Fscholar%3Fstart%3D10%26q%3DExpansion%2Bof%2Bthe%2BAztec%26hl%3Den%26as_sdt%3D1%2C33#search=%22Expansion%20Aztec%22. The Silk Road. On the eastern and western sides of the continent, the civilisations of China and the West developed.
The western end of the trade route appears to have developed earlier than the eastern end, principally because of the development of the the empires in the west, and the easier terrain of Persia and Syria. The Iranian empire of Persia was in control of a large area of the Middle East, extending as far as the Indian Kingdoms to the east. Trade between these two neighbours was already starting to influence the cultures of these regions. This region was taken over by Alexander the Great of Macedon, who finally conquered the Iranian empire, and colonised the area in about 330 B.C., superimposing the culture of the Greeks.