Milk, ping.
Horses aren't on there so maybe the artist didn't realize that they are a MAJOR source of milk in any horse culture. I can purchase mare's milk cheese in over a dozen stores in this community.
Recent in depth studies regarding the modern spread of lactose tolerance among the Sa'ami indicate that it's not exactly the auto-somal recessive it was formerly believed to be.
A single allele is enough to confer the beneficial effect on a person provided the local environment has milk available. That increases the rate of spread to near lightspeed ~ half a dozen generations and EVERYBODY's got it.
Alexander The Grate was The Mac_Cheese_Donutian who conquered the world?
All in all this is a Cheesy Post!