The name also generally describes the various northern Christian kingdoms and polities of the Iberian Peninsula since 711 (92–93 AH), though the boundaries changed constantly as the Christian Reconquista progressed. After the Battle of of Las Navas de Tolosa (1212 AD / 609 AH) the frontier between Christian north and Muslim south is permanently settled along the Tagus River and Toledo. To the south of Aragon and along the Júcar river the boundary is less settled and as changed sides several times during the Reconquista.