This sounds like you encountered some soapboxing sites and they manipulated the facts to meet an agenda.

I am going to assume that whoever authored these claims was referring to Europe after the fall of the Western Roman Empire when a significant amount of infrastructure was lost, and records with it. Now, Medieval history is not my strong suit, so I would like someone to fill in here and add/correct some details, but for one thing the "Dark Ages", the Medieval Period in Europe was not so much an apocalyptic loss of civilization as it would seem, and it seems silly to take an entire continent, over the course of a few centuries and chalk it up to barbarianism. To be fair different regions and countries did better than others, but there were plenty of folks with their own thoughts and traditions as well as people perpetuating a lot of the knowledge and culture that the Roman Empire had introduced, ie. the Vandals and other Germanic tribes that were responsible for sacking much of Rome but also first contributed to the culture and absorbed quite a bit of it, and the Eastern Roman Empire (the Byzantine Empire) which still held territories in the European continent.

The Umayyad Caliphate (I will assume this is what they are referring to) did greatly contribute to Iberian culture and being that the Umayyad dynasty came from a different region with a unique tradition and school of thought from the Visigothic Kingdom that had ruled before had plenty to introduce in terms of architecture and tradition, but that is different from civilizing a place. the Visigothic Kingdom was civilized, and it isn't like everyone in Europe just forgot how to be civilized. This is a rather arrogant assumption many historians fall into, of believing that prior to being conquered and uplifted by the superior empire that whole regions and civilizations had nothing to contribute or which made them much more than backwards provincials (you see this all the time when discussing the Roman Empire).

The term "Moor", I have my issues with as it lumps together an ethnically diverse group of people originating in North Africa who later inhabited areas of Southern Europe such as Sicily and Iberia, and who neither all looked alike or were from a uniform culture. Besides the inaccuracy of it as a term it has also become a beacon for agenda-pushers, (be they Stormfront or whatever they call themselves right now, or Afrocentrists with something to prove).