To what does the old kingdom refer?

The old kingdom is a period in Egyptian history that lasted form about 2700 BC to 2200 BC.

Explanation:

The American Civil war was the deadliest war ever fought in the United States of America. The war was fought between the Union and the Confederacy army from 1861 to 1865. The attack on Fort Sumter by the confederate militias triggered the American Civil War.

The war changed the country and has impacted the citizens to this day. America made the slave trade illegal. The country became the land of the opportunity and the rise of technology evolved drastically. The technology was used to guide how we communicate. Hospitals and ambulances were implemented in real-life situations.