Its funny that you ask this question, just as I've been explaining that the term "Islamic Golden Age" has been thoroughly debunked by so many eminent Islamic and Medieval Middle Eastern professors.
What you are usually taught in school, is that "Islam" went into decline in 1258, with the sack of Baghdad by Hulagu Khan, and his Mongols. However to say that this was representative of "all of Islam", would not only be factually wrong, but logically incorrect as well. So without giving me more information by what you specifically mean by "Islamic Golden Age", I will take it that you mean this event.
Here is what I wrote regarding it:
"To give you a proper answer: I don't like the contextualization that "Golden Ages" supposedly gives a reader, because it effectively means nothing, and does not help us understanding anything. Not to mention is gives a very Arab-centric understanding of Islam, when in fact Islam now spanned from Iberia to West/East Africa to East Asia. So did the Mongol invasions of the 1210s, culminating with the sack of Baghdad in 1258 and the sack of Damascus in 1260 mean the end or a "decline" of Islam, or its expansion? Absolutely not, in fact the reverse is true.
The arrival of the Mongols, much like the [Oghuz] Turks 200 years before, was definitely a watershed moment for the Middle East (not all of Islam). However it was the Mongols, under the Ilkhans, Chagatai and the Kipchak Khanate (Golden Horde), which helped to spread Islam, and led to a closer cross cultural exchange with [Yuan] China. Not to mention the many great works which Mongol patrons committed to, such as the great architecture of Sultaniyya or the Shahnameh, not to mention the continuous scientific work, and innovations in government administration. During the period post-1300, according to Dr. Richard Bulliet, Islam spread the fastest outside of the Middle East, and most of the world's Muslims today, come from converts, post-1300. So to say that Islam was in decline, is utterly false. For sure Baghdad went into decline, and power moved elsewhere; this had its influence limited to the Arab world, specifically the Levant and Iraq. Power bases in Delhi (the eponymous Sultanate), Cairo, Aceh, continued to grow and expand in their own right, without any interference from the Mongols."
Sources:
New Cambridge History of Islam (2010)
Richard Bulliet, "Islam, The View from the Edge"
The_turk is correct. after 1258 Islam continued to spread and develop. And to do some very impressive cultural creations. You got Mughal India, Persian history and architecture, and the Ottoman Turks and Sufis. The conquering mongols became muslim, not christian, and tied the Steppe to the Middle Eastern Cities.
But I think the question is not about "Islamic" so much as it is about Arab and thus about the Abbasid Caliphate.
So life in the Abbasid Caliphate was the best on earth at that time (until Tang Dynasty China got going). Baghdad in 900 CE was a new Constantinople, it was at the end of the Silk Road and thus the nexus of trade and ideas.
The Abbasid caliphate did not expand militarily and instead invested heavily in cultural creation. to do so It brought in ideas from all over the world. math from India (the invention of zero) created algebra, roman and greek philosophy were incorporated into Islamic theology, roman engineering was incorporated into cities.
Cordoba in far off Spain had a million people in it (paris has 5,000 where ppl threw their waste into the streets), lit streets at night, sewers, sidewalks, fresh fruit, fresh water. It was healthy and educated.
Arab Islamic civilization was as good as life got in 900 CE (if you were a citizen - but even slaves were better off than later slavery in the Americas). Businesses had a large world to trade with, wealthy ppl had diverse education available to them