Chords in D Aeolian

D Aeolian is built from the notes D, E, F, G, A, Bb and C. Its scale carries 1 flat. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Dm as the i. The chord on the fifth degree is Am rather than a major V, so D Aeolian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain D major.

Beyond those seven, D Aeolian commonly borrows D (I), Em (ii), F#m (iii), G (IV) and A (V) from the parallel major — the mixture chords that give a progression somewhere unexpected to go.