Horses allowed for intertribal diffusion of language, trade, and tradition in unprecedented ways. I recently read a very cool paper on the subject: The Politico-Economic Impact of the Horse on Old World Cultures: An Overview by Pita Kelenka [pdf link], which is from the book The Horse in Human History The author is also an advocate for better treatment for horses, one of the animals in the world most likely to suffer abuse and neglect. I am so buying this book because based the paper, it looks awesome.

For those of who write everyday with doggies at our feet, my favorite is the footnote: dogs have been with us since the Paleolithic, helping us hunt. Well, mine help me hunt words. 😉 It’s mostly moral support and the reminder that if I stop writing, my dean will become displeased with this little scholar-writer-monkey, and I shan’t have any money to buy dog food with.

Back to the material, though. I sketch a rough timeline:

4000 BC the donkey is domesticated in Nubia
3500 BC evidence of mare’s milk use in Botai, though this conclusion is controversial (Botai was what is now Kazakhstan.)
2800 BC evidence of horses used in warfare (of course) at Karum Kanesh II (modern Turkey)
2100 to 1800 BC first clear pictorial evidence of horse and rider in Afghanistan
2300 BC larger spread of agricultural uses of the horse and human settlement far into the Asian steppes accomplished via metallurgy and wheels
2000 to 900 spread of the Andronovo (Indo-Iranians) across Asia by chariot
1500 to 1000 BC Yaz I culture (more Indo-Iranians from the Afghan-Turkmen-Iranian border); also first use of chariots in Chinese settlements

And then more into the early Mediterraneans.