According to Scoutwiki, the song was written in 1971 by Franco Battiato and sung by "Osage Tribe", the Italian band he founded.
Also "...e quando era l'ora dell'ultimo sonno, partivo..." is ~"...and when the time of the last sleep came, I left..." and "...e verso il sole mi indicava il cammino..." is ~...and towards the sun, he pointed me the way..."