Again, Arabia is the most distant to the south of all inhabited countries: and this is the only country which produces frankincense and myrrh and casia and cinnamon and gum-mastich. All these except myrrh are difficult for the Arabians to get. They gather frankincense by burning that storax which Phoenicians carry to Hellas ; they burn this and so get the frankincense; for the spice-bearing trees are guarded by small winged snakes of varied color, many around each tree; these are the snakes that attack Egypt . Nothing except the smoke of storax will drive them away from the trees.