Quetzal (we'll call him that because you really can't pronounce his real name in Dragon) drifted into Meso-America sometime around 9000-10,000 BC. He was a young dragon who found the climate to be quite comfortable (warmth and humidity do appeal to dragons, even though we're warm blooded, unlike other surviving modern reptiles). He was young enough to still be in an experimental growth stage where he was changing shapes a lot to test his abilities and to find his identity. Happenstance was that when he first made contact with the early Mayan hunter-gatherers he was in the form of a large serpent with colorful feathers (although he would also change into a jaguar, human or other shape as he desired).
Needless to say, the locals were rather surprised when they first came upon him. In fact, they were rather inclined to use their weapons upon the large serpent (potential food, and potential danger). Using his dragon abilities to change, he made himself impervious to their weapons and then rose above them -- a rather unsettling experience for the Mayans -- to see their weapons just bounce off of him, and to then see him essentially levitate. Being rather sensible, they turned tail and ran, headed back to their village for re-enforcements. Changing into a large bird, Quetzal just floated along behind to see where they were going.
The Mayan village was rudimentary at best (more a camp), as they were roving hunter-gatherers. Quetzal settled into the branches of a nearby tree to observe. Initially there was a lot of commotion (to be expected when happening upon a huge feathered serpent that is impervious to weapons and levitates). A larger party was organized and set out to retrace the steps of the original hunting party. While they were gone, Quetzal made himself small and flitted down into the village. He listened to the conversations going on around him -- and even more importantly, he tapped into the ley lines and telepathically listened in on the thoughts surrounding him, picking up the rudiments of the language and the Mayans concerns (primary topic being a large, flying feathered serpent).
Quetzal, being a typical inquisitive (i.e. nosey) dragon, decided to follow groups of men as they wandered from the village on hunting forays, observing their techniques and habits. He also followed the women as they wandered, gathering food-stuffs from the jungle and preparing the meals upon their return to camp. He also observed other bands in their territory, noticing occasional friendly contact.
As any dragon would do while watching the band for several months, he would frequently blip off to hunt or relax elsewhere (and else when), returning when he wanted. Over time he acquired a reasonable knowledge of their language and customs and eventually decided to insert himself into their community (I did mention nosey, did I not).
Unlike some earlier-mentioned male dragons who had taken over early hominid groups, Quetzal decided to try a different approach. He set up a primitive camp in an area in between three different bands.
His camp was actually sort of a lab situation. He set up a couple of rudimentary plots where he planted some wild versions of a couple grains, some melons and beans, and some chili peppers -- all of which he had seen the Mayan women gathering in the jungle and open areas around their camps. Never having done anything like this before, he blipped into other areas around the world to see what folks were up to in those areas, checking in with dragons in Mesopotamia, Egypt, China and elsewhere in North America. During his travels he noticed various farming practices being developed and so tried some rudimentary irrigation (running water from a nearby stream to his crops).
As expected, his little campsite and garden plot was eventually found by wandering hunters who were quite surprised to see him (in his human -- Mayan -- form) tending the plants. As he was by himself, the hunters were not too concerned and approached, questioning him about the plants in their obviously artificial setting.
