This means that different people perform specialized tasks. In a purely agricultural society, members of the community are largely self-sufficient, and can provide food, shelter, and clothing for themselves. In a complex civilization, farmers may cultivate one type of crop and depend on other people for other foods, clothing, shelter, and information.
Civilizations that depend on trade are specially marked by divisions of labor. The city of Timbuktu, in what is now Mali, was an important trading center for several African civilizations. Residents of Timbuktu specialized in trading such goods as gold, ivory, or slaves. Other residents provided food or shelter for trade caravans traveling on camels from the Sahara Desert. The urban center of Timbuktu was also a center of learning. Its division of labor included not only merchants, but doctors, religious leaders, and artists.