He returned as governor in 1612. Father Luis de Valdivia had specifically requested his appointment from King Philip III. Valdivia was the originator of a new system of defensive warfare in Chile. He planned a static frontier separating the Spanish zone from the Indigenous zone, permitting no one but missionaries to enter the south from the Spanish side. The king was in agreement, and although Ribera himself did not totally agree, he followed the royal orders and established the defensive system.