There is a limit to the size of a group that can be formed and maintained before its social order destabilizes and another group is formed. A project team of 100 members requires 4,950 one-to-one relationships (formula:
Zoologists found only a handful of chimpanzees groups larger than 100. And that ended up with warfare and even genocide.
Humans have the advantage to use imagined order (myths, legends, countries, beliefs), thanks to the cognitive revolution, to form and rule extremely large groups of people.