It gave them things to trade with other countries and themselves in order to establish kingdoms
It was right in the middle of the Bosporus, Black Sea and the Mediterranean Sea. So, all trade between North Africa, Asia and Europe, had to pass through the capital (Constantinople), causing the Byzantine Empire to become very wealthy due to taxes they charged between the trading.
Nuclear fear led to a new market for fallout shelters. Home economics classes taught girls how to stock such a shelter with food and supplies in the event of a nuclear attack. The government created official films on shelters, praising their value and advising homeowners on how to use them.
The Cold War, The Death Count (70 million), Also it shaped our world to develop Nukes!