Em7 to B7 chords, repeated, over a funky latin type groove. Ideal for introducing the harmonic minor scale.
The Em7 sets it up as a minor progression, whilst the B7 introduces an E flat note. The harmonic minor scale is identical to the natural minor scale aside from one note - it has a major 7th instead of a flattened 7th.
Check out my 'Introduction to harmonic minor' tutorial for further insight.