Trade in Maya civilization was a crucial factor in maintaining Maya cities. Chief staples of Maya economic activities were centered primarily around foods like fish, squash, yams, corn, honey, beans, turkey, vegetables, salt, chocolate drinks; raw materials such as limestone, marble, jade, wood, copper, and gold; and manufactured goods such as paper, books, furniture, jewelry, clothing, carvings, toys, weapons, and luxury goods. The Maya also had an important service sector, through which mathematicians, farming consultants, artisans, architects, astronomers, scribes and artists would sell their services. Some of the richer merchants sold weapons, gold and other valuable items.