What is the relevant background that I need to know to understand the story "Marriage is a private affair" by Chinua Achebe?

This is a very important question concerning the African
literature that authors such as Chinua Achebe and Ben Okri produce. For us to be able to
understand the context out of which a particular story has emerged enriches our
comprehension of what the author is trying to convey, however, often, especially for
Western readers, we are unaware of the contextual background which is used as the arena
for the conflicts described in such tales as this
one.

Chinua Achebe, himself a Nigerian, chooses to set this
story in Nigeria, a land marked by ethnic diversity. Nigeria has more than 250 ethnic
groups and these groups are distinct in terms of their culture and language as well as
religion, customs and traditions. The two tribes mentioned in this story, the Ibo and
the Ibibio, come from southeastern Nigeria, but traditionally did not marry. This story
tells the tale of a young Ibo man and a young Ibibio woman who have moved from their
native regions to Lagos, a large, modern city in southwestern
Nigeria.

Thus when these two individuals fall in love and
want to marry it causes great problems with the boy's father, who wishes traditions to
be maintained and his son to marry an Ibo woman. The story thus focuses on entrenched
cultural traditions about marriage and family, and most importantly, in the figure of
the father who relents in order to get to know his grandson, the cost of maintaining
those traditions even at the expense of losing your son and never knowing your
grandchildren. Consider the final paragraph of the story, told looking at the
father:

That
night he hardly slept, from remorse - and a vague fear that he might die without making
it up to them.

Achebe thus
exposes the cost of pursuing a tribal, traditional view by focussing on the human
casualties rather than bigger metanarratives that are still vitally important in Africa
today such as tribal purity and segregation.