Final answer:
Highly developed urban centers in Africa existed as early as 900-800 B.C., with notable cities like Djenne-Djenno in Mali flourishing by the 9th century. These centers exhibited complex urban planning, trade, and agriculture, similar to developments in other ancient civilizations.
Step-by-step explanation:
Highly developed urban centers were present in Africa as far ago as 900-800 B.C. Agricultural expansion and intensification led to the rise of walled villages, and by 700 B.C., this gave way to numerous unwalled villages, laying the foundation for future urban centers. The early city of Djenne-Djenno in Mali is one of the oldest known cities in sub-Saharan Africa, flourishing as an urban center by the 9th century. Urban centers in Africa featured administrative capitals, craft specialization, regional trade, monumental architecture, and agricultural surplus, demonstrating sophisticated urban planning and societal organization. The emergence of large kingdoms and city-states by the mid-fifteenth century, including Ghana, Mali, Songhay, and the city states of the East African coast, mirror the development seen in other early civilizations across the world.