In the span of nearly 15 years, Prodigy and The Alchemist's musical output has been nothing short of astounding. The Mobb Deep veteran and Los Angeles underground alum have clocked in two full-length albums, hundreds of one-off collaborations and a mind-boggling amount of hit singles given their decidedly non-mainstream sounds. Yet through all the label change-ups and legal drama, the duo have maintained a constant sonic cohesiveness that escapes most hip-hop duos.

"In the past, working with other companies [there] was this pressure we always felt, we had to conform or whatever," Alchemist said. "This [album] is like, yo, we really run this. This is our decision. It’s up to P and whoever else is in the camp, and that’s how we made the record. We didn’t have to answer to no group."

Now, with their second collaborative effort, Albert Einsteinhitting store shelves today via Prodigy's own Infamous Records, P and Al are looking forward. "Where Alchemist is at right now and where I’m at right now lyrically, it’s not like, 'Oh this is what the sound of right now is,'" Prodigy said. "This is the sound of us right now. This is the sound of our hardcore hip-hop right now and to the future."

Yesterday, XXL sat down with P and the A-L-C to break down their long history and their three favorite tracks together. From channeling the sounds of Blaxploitation cinema on Return Of The Mac to Prodigy drinking bong water, here are some of the pair's most meaningful collaborations and some of their best stories.