“Mountain Jam” is an improvised instrumental jam by The Allman Brothers Band. The song’s first known recording is on May 4, 1969 at Macon Central Park. “Mountain Jam” was originally released on the 1972 Eat a Peach album, as recorded at the Fillmore East concert hall, in March 1971. That is the rendition that is best known.
Other live recordings have been released on the albums Fillmore East, February 1970, Live at Ludlow Garage: 1970, Live at the Atlanta International Pop Festival: July 3 & 5, 1970, The Fillmore Concerts, and deluxe edition of At Fillmore East (1971). Notably, Live at the Atlanta International Pop Festival: July 3 & 5, 1970 contains two recordings of the song (the second of which features guest musicians Johnny Winter on slide guitar, and Thom Doucette on harmonica).
In fact it makes its first appearance at the end of 1971’s At Fillmore East when its first notes are heard and then faded out when it is started immediately out of “Whipping Post”.