The Yanomamö simply killed each other efficiently enough to keep populations down. In practice they ran into violent neighbors long before they ran out of land to farm och game to hunt. For security reasons they had to leave large swathes of land as buffers between villages.
That's the result of the lack of politics, what you are referring to is policies that kept the different groups separated based on their choices or caused splits among them.
Hammurabi was a great politician because he reunited the Mesopotamian tribes in a single state city, convincing them to work for a common goal, making them all prosper together.
The Yanomamo were one of probably thousands of different groups that lives in the prehistoric era. One problem in the study of prehistoric human life is that only a few groups kept their way of life consistent from prehistoric times to modern. So these groups have strongly influenced our perceptions of what life was like in the prehistoric era. But this is inaccurate sampling if we want to draw conclusions about prehistoric life. More nuanced looks at the evidence, such as the dawn of everything, find more diversity, including politics among different groups in the prehistoric age.
