This is an instrumental piece that began as a jam session in San Francisco.
Santana played this at Woodstock, creating one of the more memorable moments of the iconic festival. The crowd was chanting "No rain" just before the song started, and the chants segued neatly into the percussion intro to the song.
The Woodstock version of this song is included in the 30th anniversary re-release of Santana's debut album as a bonus track along with live versions of "Savor" and a previously unreleased jam "Fried Neckbones and Some Home Fries."