The period from 600 to 1450 AD is commonly known as the ‘Dark Ages‘. At best this is a Eurocentric term. Even in Europe, under the feudal system, there was little warfare until the 14th century.
In the Islamic world, there were huge cultural and political advances. The Ummayad dynasty took Spain, but were supplanted in 750 by the Persian-influenced Abbasids, who presided over a golden age of artistic and intellectual endeavour, developing algebra, adopting the zero from Indian mathematics, and producing wonderful poetry, art and architecture. They also translated great philosophical and medical texts from Greek.
The Chinese were also experiencing a ‘golden age’. Their art was traded everywhere, as was their beautiful blue and white porcelain. In the 11th century they invented paper money and gunpowder.
Dark Ages? Taking a balanced view of world history, far from it.