I've heard it prospered.

It did.

The Dark Ages (Middle Ages) are commonly referred to as the, "Golden Age" of Islam (8th-15th century).

During this timer period, the fledgling Muslim Empire(s) spread from a stretch of desert in the Arabian Peninsula, to the Middle-East, North Africa, Eastern Europe, and South/Central Asia.

With some help from ancient Greek and modern Chinese sources, this rapidly expanding empire soon became the center of scientific/cultural progress. Great strides were made in the fields of Algebra, Astronomy, Medicine, Art, and Architecture, while these societies were also some of the most socially progressive/tolerant of their time.

In short, during this time period the Muslim world was essentially the center of the world, whether it be in the battle-field or in the class-room