Wow... Not a big topic... A HUGE topic!! lol

Ok here goes :

the minor pentatonic is minor, therefore built off of a natural minor scale. It's actually a natural minor scale minus the second and sixth degree. But here's where it becomes interesting : the natural minor scale is built off of the major scale. It's actually the major scale played from its 6th degree. Check this out :
notes from the C major scale ( 2 octaves ):

C D E F G A B C D E F G A B

Now notes from the A natural minor scale :

A B C D E F G A B C D E F G

They're the same scale. They only have a different ROOT note. That's what a mode is. A mode is simply an "inversion" of a scale, shifting the natural root to a new one contained within the original scale. A natural minor is also known as the aeolian mode which is basically a major scale played from its 6th degree. To make sure you understand correctly, play your standard C major scale over the C major chord and listen how happy and positive it sounds... Now play the exact same C major scale over an A minor chord and notice the totally different mood it produces... Welcome to the world of modes... Exotic scales are their own scales or variations of other scales. Minor scales other than natural minor are alterations of the natural minor ( ex : harmonic minor is the same as natural minor, only with a raised 7th degree )...

Of course the major pentatonic is based off a major scale...