Impossible question to answer.

I would possibly say that when music was first typeset - the 30 years that included that - could be considered the most important. Music could then be shared.

I could say it was the 30 years that included when Les Paul practically invented the electric guitar AND multi-track recording.

I could say it was the 30 years that included the launch of the Macintosh and the IBM-PC.

I could say it was the most recent 30 years - as it democratized the distribution of music, at least to the part of the world with access to the Internet. I've been able to 'play' my music for those of you here - some in Austria, Australia, Belgium, Canada, Deutschland, England, Finland, Georgia, Hungary, Italy, Japan, etc. And I have had listens by folks from all of those places. The Internet made it possible for me.

Those are just technology reasons for answering the question.

Stylistically - I think that this is up to the listener. I could pick any 30 year period of music that I listen to or has heritage from, and make up reasons for why it's the most important - including the most recent 30 years.

-Scott