Incomplete questions. Here is part of the complete questions:
Answer:
1. the Nile
2. strict social structure of India
3. Timbuktu
Explanation:
1. We can rightly make this conclusion because even though the Nile is a major river, it is actually located in the continent of Africa, (specifically northeastern Africa).
2. Indeed, the caste system was introduced in. This system requires a strict social structure, in which individuals in the society are ranked by their status etc.
3. The African country of Timbuktu had a major role in African trade, it became a center for African trading. It also contributed to learning and culture.