Watch the A String Drone online guitar lesson by Joe Dalton from Fretboard Epiphanies
Even though these are the chords from the E major scale, they have a distinct A tonality because of the bass note. For instance, the first chord is an A major ninth. The root and fifth are present (the A and the E), but the G# and the B are the major 7th and 9th. That’s why it is an Amaj9.