That "Islamic Golden Age" is a complete misnomer. It hides the religious diversity of the geography. Many don't know that it took many centuries for the majority of the population of the Iranian plateau to convert to Islam. For a good part of what is referred to as "Islamic Golden Age" Islam was not the dominant religion.
Similar story applies to India. Up until 17th century, India was ruled by "muslim" rulers. Should all the cultural and scientific achievements of that period be attributed to "Islam?"