How accurate is the following article from Wikipedia?:

The Ogoni languages, or Kegboid languages, are the five languages of the Ogoni people of Rivers State, Nigeria.

They fall into two clusters, with a limited degree of mutual intelligibility between members of each cluster. However, the Ogoni think of them as separate languages.

The Eastern languages are Khana, with a quarter million speakers, Gokana, with about half that number, and Tẹẹ, with an unknown number. The Western languages are Eleme, with about 70,000 speakers, and Baan, with about a tenth that number.

How can such a small place develop such different languages?

ezeagu:

How can such a small place develop such different languages?

Traditions have it that some Ogoni are actually strangers to the area. They are said to have arrived by boat, at Bonny, where they were then allowed to stay for a while until Bonny moved them further inland, where they are said to have settled with amongst some 'original' settlements. Another tradition says that some Ogoni came from Ibibio. Another tradition claims origination at their locality, but this origination claim relates so much with the Ibibio one that it becomes a bit doubtful.

Those are dialects and not languages.

ChinenyeN:

Traditions have it that some Ogoni are actually strangers to the area. They are said to have arrived by boat, at Bonny, where they were then allowed to stay for a while until Bonny moved them further inland, where they are said to have settled with amongst some 'original' settlements. Another tradition says that some Ogoni came from Ibibio. Another tradition claims origination at their locality, but this origination claim relates so much with the Ibibio one that it becomes a bit doubtful.

That would explain it.

afam4eva:

Those are dialects and not languages.

The dialects are different enough.