When

The art rock era began on March 14, 1966, when The Byrds release "Eight Miles High" as their latest single. The art rock era ended, if it has ended, when the rock era ended, sometime around 2017 or 2018.

Why "Eight Miles High"?

The song combines a droning vocal melody and guitar playing, and by the John Coltrane-inspired guitar breaks and solo. It is the combination of the Byrds' folk rock with the influences of Indian music and Indo Jazz. It was a Top 15 single in the United States and a Top 25 single in the UK. (It was banned in many states, so the theory is it would have reached the Billboard Top 10 if it hadn't been banned.)

Previous singles had featured Indian influences, particularly The Kinks' "See My Friends," released on July 30, 1965, and the Yardbirds' "Heart Full of Soul," released June 4, 1965. But both songs are significantly less radical than "Eight Miles High"; "Heart Full of Soul" is still pretty much blues based and "See My Friends" is liked "Eight Miles High" without the Coltrane.

Why a single?

The early psychedelic albums all feature stabs at psychedelia paired with more traditional music. The Byrds' single is very much a departure from previous music and there is no doubt.

Why the release date, not the recording date?

The first version of "Eight Miles High" was recorded in December 1965 but it was never released because of a contract dispute around where it was recorded. (The Byrds' label didn't own the studio.) Nobody heard it therefore it doesn't matter. The official version was recorded in late January 1966 but, again, nobody heard it until it was released in March. Art is social; music must have listeners for music to matter.

Why use psychedelia?

Psychedelia was not the first time art music and popular music were combined. There were at least three previous instances: