Five years later, I finally found this. I think the version I heard must have been slightly different because my lyric prompts above use different terms. But this is definitely it. It's actually called "There once was a people". Full lyrics:

THERE ONCE WAS A PEOPLE

There once was a people
Of blood that ran strong
Travelling people
Of story and song
They lived their lives
True to the wisdom gone by
They spoke their own tongue
Beneath the clear sky

Now those who were young
Would be hushed off to bed
At night by the fire
The pipes could be heard
It was the sound of the wind
And the trees and the stream
And the moonlit night
Where the banshees scream

And the old folks would tell
Of the magic long gone
Of the elves and the fairies
Their laughter, their song
Of the stones of midsummer
And the power within
Of the travelling people
And the places they've been

Now come around people
In this time-honored place
Down in the hollow
Beneath the moon's face
Don't need much money
For the road isn't poor
So come with me together
We travel some more

Leave the stinky black town
Of the civilized man
Where black tar and concrete
Have strangled the land
Come out in the open field
Running with me
And together we'll find
What it is to be free

I could only find one attribution: https://lyricstranslate.com/en/rainbow-songs-there-once-was-people-lyrics.html