You're just living your life as you do, as did your parents before you and their parents before them. But some new people make contact...people who look so different and yet also seem human. In Things Fall Apart, Achebe tells a story of how things may have gone following European landings near villages in Africa hundreds of years ago.
Of course, you've probably already heard tales of how things seemed when Europeans landed in Africa. But you would likely have received the European perspective. This novel is from the point of view of an African village and one of its leaders, who is the novel's protagonist.
In the first half of the book, nothing seems to happen, which left me somewhat frustrated/bewildered. But I think this "time" is taken to accustom the reader to the village's culture, which is very different from our own. Once you are immersed in village customs, only then does it make sense to introduce the colonizers, who have very different ideas about how things ought to be.
Apparently, it is a staple book in schools in Africa, and I highly recommend Things Fall Apart to anyone interested in the topic.