Learn French: Il a habité à Madagascar, et il s'en souvient très bien. - He lived in Madagascar, and he remembers it very well.

Even though Madagascar is a country, it is also an island that doesn't use a definite article (it is just Madagascar, not la Madagascar). In French, singular islands without an article take the preposition à to mean in or to. Other examples include à Cuba or à Malte.

Why is there an en in il s'en souvient?

The French verb for to remember is se souvenir de. Because it is followed by the preposition de, we use the pronoun en to replace de plus the thing being remembered (in this case, his time in Madagascar). So, il s'en souvient essentially means he remembers of it.

Why does en go between s' and souvient?

In French, object pronouns like en must be placed immediately before the conjugated verb they belong to. When a verb is reflexive like se souvenir, the reflexive pronoun (se or s') comes first, followed by en, and then the verb.

Could we use the imparfait (il habitait) here instead of the passé composé (il a habité)?