. ▁Other ▁wars ▁led ▁to ▁the ▁Northern ▁Cr us ades . ▁The ▁Christian ▁kingdom s ▁took ▁much ▁of ▁the ▁I ber ian ▁Pen ins ula ▁from ▁Muslim ▁control , ▁and ▁the ▁Norm ans ▁conquer ed ▁southern ▁Italy , ▁all ▁part ▁of ▁the ▁major ▁population ▁increases ▁and ▁the ▁res ett lement ▁patterns ▁of ▁the ▁era . ▁ ▁The ▁High ▁Middle ▁A ges ▁produced ▁many ▁different ▁forms ▁of ▁intellectual , ▁spiritual ▁and ▁art istic ▁works . ▁The ▁age ▁also ▁saw ▁the ▁rise ▁of ▁eth noc entr ism , ▁which ▁evol ved ▁later ▁into ▁modern ▁civ ic ▁national isms ▁in ▁most ▁of ▁Europe , ▁the ▁as cent ▁of ▁the ▁great ▁Italian ▁city - states ▁and ▁the ▁rise ▁and ▁fall ▁of ▁the ▁Islam ic ▁civil ization ▁of ▁Al - And alus . ▁The ▁redis cover y ▁of ▁the ▁works ▁of ▁Arist ot le , ▁at ▁first ▁indirect ly ▁through ▁Med ieval ▁Jewish ▁and ▁Islam ic ▁Philosoph y , ▁led ▁Ma imon ides , ▁Av ic en na , ▁Muhammad ▁A ver ro es , ▁Thomas ▁Aqu inas ▁and ▁other ▁think ers ▁of ▁the ▁period ▁to ▁expand ▁Sch ol astic ism , ▁a ▁combination ▁of ▁J ude o - I sl am ic ▁and ▁Catholic ▁ide ologies ▁with ▁the ▁ancient ▁philosophy . ▁For ▁much ▁of ▁this ▁period , ▁Constantin ople ▁remained ▁Europe ' s ▁most ▁popul ous ▁city , ▁and ▁By z antine ▁art ▁reached ▁a ▁peak ▁in ▁the ▁ 1 2 th ▁century . ▁In ▁architecture , ▁many ▁of ▁the ▁most ▁notable ▁Goth ic ▁c athed r