Question

Between 500 and 1450, a rivalry developed between the Christian European states and

Answer 1

between 500 and 1450 a rivalry developed between the Christian European states and Muslim African and Asian states

Answer 2

Between the Christian European states and the Islamic states of the Middle East and Africa. This has commonly been also known as the Crusades which started around the 10th century in the Middle east and have continued for a couple of centuries before losing their momentum.