Domaine de Sivas is easily reached by train. You either come from Marseille, Valence or Grenoble and get off at the Veynes-Devoluy train station. These three cities are easily reached with high-speed trains.
For detailed information on train schedules you should look at the website of the french railways (SNCF).
If you provide us with your arrival time, we will pick you at the Veynes train station. Note however that you have to take your provisions with you, as there are no shops within easy walking distance. We therefore urge you to rent a car in Gap.