>> Two characters regularly found in the mud of Mesopotamia, particularly in the upland areas to the North, are minatures of both reindeer and an elderly, jolly gentleman with a white beard. <<
The use of the word “jolly” is used to invoke Santa Claus. Guess what? Elderly men have white beards. Please tell me your evidence is not that a reindeer-herding people had depictions of both old men and reindeer.
Although mankind has been following reindeer herds around for far longer than just about any other similar animal, the first domestication attempts came quite recently. They were forced by political reality ~ the arrival of "civilization" to any region means you can't just follow the animals around ~ you must begin to control their movements if you wish to assert continued ownership.
The Sumerians built permanent cities yet they continued to follow the herds. Guess there were no "outsiders" trying to take their lands.
Things were different in the beginning.