Final answer:
Sophisticated ironworking technology developed independently in Central Africa, specifically in modern-day Chad, the Central African Republic, and South Sudan.
Step-by-step explanation:
The region of Africa where sophisticated ironworking technology developed independently is Central Africa. It was previously believed that ironworking technologies spread to other parts of Africa from Egypt, but modern scholars now agree that iron smelting in sub-Saharan Africa likely preexisted its introduction into Egypt. The earliest evidence of ironworking in Africa dates to about 1000 BCE and comes from modern-day Chad, the Central African Republic, and South Sudan. From there, the technology spread west to the Niger River area and was used by the Nok culture in West Africa by 500 BCE.