They were found in Central Asia among the nomadic pastoralist. Today, they are very common because they are referred as man's best friend and they are household pets. They are also domesticated.
What role does a dog play? They protected livestock and property. The dog was the first domesticated animal and has been widely kept as a working, hunting, and for companionship. The dog is also used for police activity to help sniff drugs and find bombs. It is used for more reasons.
Do you think the use of this animal changed through history? Yes, because first they only used them for hunting and companionship. Through time they have started using the dogs for more uses.
Why might this animal be especially valuable to a nomadic pastoralist? They would travel with the people and they would help with loneliness. And they would help herd the other animals and help find food.