Read the excerpt from chapter 8 of The Travels of Marco Polo.This province produces great quantities of excellent white incense, and also dates in great abundance. No grain is grown here except rice, and not much of that; but it is imported from abroad at a big profit. Fish is plentiful, notably tunnies of large size, which are so abundant that two of them can be bought for a Venetian groat. The staple diet consists of rice, meat, and fish. . . . As for the incense of which I have spoken, which grows here in such profusion, the lord buys it for 10 gold bezants a cantar and then sells it to foreign merchants and others for 40 bezants a cantar. The lord of Shihr does this on behalf of the sultan of the province of Aden. For the sultan of Aden has incense bought up throughout his dominions at the price of 10 bezants and afterwards sold at 40 from which he derives an immense profit.