In 2079, the military conflicts of the three major powers China, Russia and the United States escalated. In the course of these military conflicts it came to the first nuclear world war. Mankind was close to extinction, the remaining powers retreated into underground bases to protect themselves from the radioactive radiation.
Those still living on the surface slowly turned into horrible creatures. These mutant clans organize the surface for 40 years. The radioactive foullout changed the DNA of plants, animals and everything else. It could die to a masses and few survived.
Forty years after the nuclear war, they came out of their bunkers to fight against the surface-living mutants. But only survivors survived anxiously.
In 2179, 100 years after the Third World War, they encounter each other again. But this time they faced a new enemy. Series 9 agricultural robots formed an army. They vowed revenge on those who destroyed their fields, took their harvest and their existing foundations.
In 8 years, the series 9 splitter group, series 21, managed to drive the survivors and evolved away from the Eurasian continent. The Human Race seems to have created an adversary against which they no longer arrive.
The last survivors retreated to the American continent while the evolved clans found their new home in Africa and Australia. Both factions are facing final annihilation but working together to destroy Series 21 is not possible.
Some groups just don't get along.