Teotihuacan is long, long abandoned by this point, at least 700 years, and the Maya are on the far side of Mesoamerica. If they are coming from the north by land, the closest might be the Tarascans or Otomis, though neither are really significant even by Mesoamerican standards. The biggest powers close to them are the various Nahua states around the valley of Mexico, and the Mixtecs. The largest city in Mexico at this time is Cholula, although it is currently under the control of Xuexotzingo. Most of the Valley is ruled by Azcapotzalco, though in 1427 they were overthrown by an alliance between Tenochtitlan, Texcoco, Tlacopan, Xuexotzingo, and Chalca. The Mixtecs are still rather divided, Tilantongo has the greatest royal lineage and probably commands the most authority, but Coixtlahuaca is also a very strong power along with Tututepec. Zapotecs are also a moderate power of the region.
Interesting I concede my mistake. I assume the Chinese would be drawn toward the great silver mines in North Mexico thus make contact with the Tarascans or Otomis and probably dominate them. I could see the Chinese making up the local elite while the natives serving as laborers and more importantly as merchants. If the Chinese bring Polynesians with them to that would be an interesting society indeed. I assume the Mexica would probably immigrate into this region instead of going to Tenochtitlan as well.