Acacia gum has been harvested in Arabia, Sudan, and west Asia since antiquity, and sub-Saharan acacia gum has a long history as a prized export. Traditionally harvested by semi-nomadic desert tribes on their travels, acacia gum is a main export of several African nations. The hardened gum is collected in the middle of the rainy season (harvesting usually begins in July), and exported at the start of the dry season (November).