Pigs were first domesticated 9000 years ago in China. Recently, however, archaeologists have found the remains of a domesticated pig in Turkey, which belonged to 10,000 years ago.
The ancient Iranians saw boars (wild pigs) as the symbols of power and fierceness. So boars' images were widely used in the art. For example, this seal impression (on the right) from Achaemenid dynasty shows a man hunting a boar.
Later, the Sasanians continued the tradition of using boars in their art. This 4th century Sasanian silver and gold plate, for example, shows King Shapur II (309-379) hunting boars.