Re: Islamic Golden Age
Sufism is a later phenomenon and the first famous Sufi we know is Mansoor Hallaj who lived during Abbasid Caliphate. Although some people believe that Sufism existed from the inception of Islam.
What is the basic theme of Vedanta philosophy that you find similar to Sufism?
Re: Islamic Golden Age
Concepts of Pantheism and the belief that everything is an aspect of God. Also the concept of validity of all religions as promoted by Ibn Arabi . "Beware of restricting yourself to one particular religion and disbelieving in everything else, so that great good would be missed by you, indeed you would miss attainment of knowledge of the affair in the form he is following. Rather be ready to accept all forms of belief. This is because Allah is higher and greater than to be comprehended by one belief to the exclusion of others. Rather all are correct, and everyone who is correct receives award, and everyone who is rewarded is fortunate, and everyone who is fortunate is one with Whom He is pleased."
I had to look up the above quote for the exact wording but I remember discussing this with my friend a long time ago.
Like I said I have only superficial knowledge in Sufism and Vedanta and I may be wrong about this.
Another similarity is the Bakthi movement. I am not sure if bakthi movement was inspired by sufism or vise versa but the concept of importance of Bakthi(devotion) over rituals were dominant in some schools of thought even before the movement started.
Re: Islamic Golden Age
The people who oppose the Sufism claim that it got its roots from Hindu religion, while the supporters of Sufism say that 'There is No Tareeqa against Sharia', - no Sufi Order act against Sharia. :)
If we see contribution of Sufism, it definitely portrayed the tolerant and accommodating perspective of Islam.