Earth is still considered a special place since it was the birthplace of humanity. However, the planet is a shell of its former self before the Great Darkness consumed all occupied space.
During the Time of Forgetting, Earth was controlled by opposing regional powers. After thousands of years slowly pulling themselves back to a technological society and reverse engineering basic Old World technologies such as agriculture growth and construction. Earth had many powerful rulers spread out across the entire planet besides the wasted regions of yellow haze.
Warlords, wealthy families, criminal organizations, and smaller groups were in control. During that time, the ruling body of each group started to form coalitions with each other. As the mergers grew in size and the number of people under the main body increased, those who would become Tier One came up with a new way of managing the masses.
The caste system was born from that time in history, and Earth became civil. When the fighting stopped, Civil Earth was born and left the Great Darkness during their Age of Innovation.
Because of planetary conditions, Earth in numerous locations around the planet, most Civil Earth citizens live in megastructures within the megacities. The population structures can house over ten thousand people each, and cities have thousands of these buildings.
These cities were built on contamination zones where the yellow haze poisons people’s lungs over a prolonged period, and the ground cannot sustain vegetation. As long as people within the caste system stay inside their buildings, they’re safe.
The lower caste system dwellers of Civil Earth who find themselves pushed out to the surface rarely survive more than a year from the roving gangs, lack of food and water, and haze that slowly poisons them to death.
All that’s known about the yellow haze is that a triggering event caused the entire planet to suffer in specific regions, and that time was the start of Earth’s Great Darkness when the Titans disappeared and death followed.
All lands unaffected by the yellow haze are used for food growth and vacation destinations for Tier One.