For example, Mérida, Cordova, Toledo, or Narbonne were conquered by storm or after laying siege on them. The arrangement reached with the locals was based on respecting the laws and traditions used in each place, so that the Goths (a legal concept, not an ethnic one, i.e. the communities ruled by the Forum Iudicum) continued to be ruled on new conditions by their own tribunals and laws.[42] The Gothic Church remained in place and collaborated with the new masters. Al-Andalus or Muslim ruled Iberian peninsula, was conquered by northern Christian kingdoms in 1492, as a result of their expansion taking place especially after the definite collapse of the Caliphate of Cordova in 1031.