Islam did not ‘help’ bring about the ‘Dark Ages’ - it caused them.
Mohammad and his Disciples (aka, the Varsity) conquered all of North Africa (which had been the grain basket to the rest of the word), stripped all the vegetation using vast herds of goats, turning it into semi-arid desert we see today; conquered the mid-east and Persia; pushed into modern Turkey, Spain, France, Greece before being repelled; along the way they destroyed everything which was not mentioned in the koran, and everything which was as superfluous.
When they had finished Classical Wester Civilization was destroyed, as was Classical Christianity. Most of the works authored by Greeks and Romans were burned with only a few surviving mostly in monasteries untouched by the devastation. They were also responsible for the destruction of what remained of the Library of Alexander after the Romans accidentally torched the place.
Last but not least the Varsity introduced the slave trade - not the sort practiced by the Greek or Romans - but people as property to be bought sold on whims and used for any purpose. This became the big business of the period - Europeans et al pilled into the lucrative trade of selling young boys and blond girls into sexual slavery in various harems. This took almost exactly 100 years. (We are, by some estimates, into the same period by 25 years of so with another 75 to go unless Islam is totally destroyed).
See the excellent series by Bill Warner on YouTube (https://www.youtube.com/watch?v=Yl_rzkutijQ - Why We Are Afraid: 1400 Years of Fear ) or his site: https://www.politicalislam.com/author/
North Africa was first taken by the Vandals and other barbarian tribes from Europe around the same time as Rome itself. Their rule was so poor that the North African subject populations practically welcomed the outside invader that was Islam.