The setting contrasts two regions of Nigeria. On the one hand, we see the rural Ibuza, where traditional values and lifestyles are still maintained. Ibuza is contrasted with the urban Lagos, where traditional values are giving way under the pressures of Western education, capitalism, and the mixture of various cultures (Hausa, Yoruba, Ibo, and European).
In rural Ibuza, families know each other for generations, and marriages are arranged by fathers. Men pay bride prices, and take multiple wives, creating a compound with many huts for their many wives. They farm the land, hunt animals, and worship their ancestors. Many men own slaves, often taken during raids in neighboring villages. Women know their social status as senior or junior wives. The number of male children a woman bears is also important in determining her status and respect as wife. The wives in polygamous unions work together, not exactly as one big happy family, but through an ordered system understood by all. Education consists of boys learning how to farm male crops (the yam) and hunt from their fathers, and girls learning how to farm female crops as well as how to make desirable things for barter and trade.
In Lagos, some of these values still persist, but they're distorted. Men work as servants for European families, and their wives question their manhood. Many men turn to Christianity in order to secure or maintain employment, so polygamy is less prominent, although it still exists. Children are educated to read, write and do math in European-style schools to read, and this process alienates them from their illiterate parents. Often children absorb European values and fail to adhere to their duties as traditional Ibo children. Women create businesses, sometimes similar to ones they might have run in Ibuza, but husbands demand a larger share in those profits. Urban life offers women the possibility of more independence if they're single.
By contrasting these two regions, Emecheta drives home her point: poverty, patriarchy, and traditional culture oppress women, but traditional culture offers safeguards entirely lacking in an urban, westernized setting.