Complex sentence: The proper term which more enlightened scholars use is Iberia, the geographical vast peninsula, encompassing Portugal, an autonomous kingdom since 1128, and several other kingdoms, these eventually aglutinated under one central power, Castille, and named Spain, after "Hispania".
Split into simpler sentences: The proper term which more enlightened scholars use is Iberia, the geographical vast peninsula, encompassing Portugal, an autonomous kingdom since 1128, and several other kingdoms. These other kingdoms eventually aglutinated under one central power, Castille, and named Spain, after "Hispania".