Tauris came first, about 414-412 B.C.; Aulis followed about 405 B.C.
In terms of the storyline, however, the order is reversed.
Aulis tells of Agamemnon’s decision to sacrifice his daughter Iphigenia in order to free the Greek fleet from the harbor at Aulis.
Tauris tells of Iphigenia after the goddess Artemis snatches her to safety, and she is reunited with her brother Orestes in Tauris.