By 1090, Ruben was not capable of leading his troops, therefore his son Constantine inherited his command and conquered the castle of Vahka. The mastery of this mountain defile made possible the assessment of taxes on merchandise transported from the port of Ayas towards the central part of Asia Minor, a source of wealth to which the Roupenians owed their power.

After his father’s death in 1095, Constantine extended his power eastward towards the Anti-Taurus Mountains. As an Armenian Christian ruler in the Levant, he helped the forces of the First Crusade maintain the siege of Antioch until it fell to the crusaders. The crusaders, for their part, duly appreciated the aid of their Armenian allies: Constantin was honored with gifts, the title of "marquis", and a knighthood.