Umuofia is the name of a cluster of nine Igbo villages located in lower Niger around the turn of the 19th century. Umuofia is also the main village and home to Okonkwo, the protagonist and tragic hero of the novel. In chapter ten, Achebe writes,

The nine villages of Umuofia had grown out of the nine sons of the first father of the clan. (39)

Most of the action takes place in the main village of Umuofia and revolves around Okonkwo's actions and decisions. Okonkwo is the most revered wrestler in all of the nine Igbo villages and also represents his village of Umuofia when the council of elders meets to resolve disputes. He has earned two titles in Umuofia, but his violent, impulsive personality leads to his tragic downfall. During a funeral, Okonkwo accidentally kills a young man and is exiled from the village of Umuofia. He is sent back to his motherland, a little village named Mbanta. When Okonkwo returns from his exile, he discovers that the European colonists have dramatically changed Umuofia and reacts with violence.

I think Umuofia is a village. The story of the novel Things Fall Apart takes place in the Nigerian village of Umuofia in the late 1880s, before missionaries and other outsiders have arrived.