These two musicians' stopped over at Bombay many, many winters ago, when they were still at the peak of their musical prowess. They loved the Maximum City so much, they decided to re-work and record some of their music in a studio in Bombay along with a local orchestra.
One of those songs came from an album much praised and loved for its "return to roots" charm (and that one scorching rocker of a song.) The other song, it came from the b-side of an album that still inspires ridiculous levels of fan-worship, nearly 35 years after its release.
So who are we talking about?
Jimmy Page and Robert Plant, playing in 1972 in the Bombay's EMI Studios with the Bombay Symphony Orchestra. (The BSO was founded by one Mr. Mehli Mehta.)
And the two songs? "Friends" (from "III") and "Four Sticks" (from "IV"). If you play the guitar, read about "Four Sticks" and feel better. It's not the easiest song to play, not even if you are playing solo.
You can find a short clip of "Friends" on this page. That's the BSO backing them.
An interview with Plant in which he talks about Middle Eastern and Indian influences on Zeppelin's music.
BTW, here's a source to get those bootlegs. (images below courtesy of the right-click and the BigO Magazine)