The cutting and shipment of wood is one of the oldest and most important aspects of Brazilian trade with Portugal. The rich red dye produced from the tree called pau brasil or Brazil wood was esteemed so highly that at first it outweighed in importance all other products of the colony. Most historians agree that the very name of Brazil is derived from this wood. Guarded as a royal monopoly throughout the colonial period, the wood trade ranked with the sugar, tobacco and gold of Brazil as one of the principal sources of revenue of the Portuguese crown. When woods for building were added to the exportation of pau brasil , the trade assumed a new importance, for these woods furnished the mother country with the sinews both of war and commerce, providing the hulls and masts of countless vessels that defended and brought together the distant domains of the Portuguese empire.