Tau Ceti Accords

The Tau Ceti Accords were a set of peace agreements between Vulcan and Andoria signed sometime before 2151. Among other things, it prohibited Andorian presence on planet Coridan.

The Andorian Imperial Guard, lead by Shran, violated these accords in 2151. 

Tau-Ceti-Abkommen Tau Ceti Accoorden