What do you call a spring of fresh water in a desert

Its called an oasis

Explanation:

the exodus of these people from constantinople contributed to the revival of greek and roman studies, which led to the development of the renaissance in humanism and science. byzantine emigrants also brought to western europe the better preserved and accumulated knowledge of their own greek civilization

the policy of appeasement influenced the beginning of ww2 because hitler gave the other countrys chocies but after they choose to try and appease hitler to not invade their country but he still invaded them.