Answer:
They are in these hunting and gathering stages because they are communities that are very isolated from the modern world and that have not been influenced by modernization, or contrary to other communities that have developed societies.
Step-by-step explanation:
There are native tribes from many countries and equally isolated communities that maintain very primitive activities and that make their living from hunting and gathering, like the ancestors of human beings. In addition to the examples given in the question above, we can mention indigenous tribps in Brazil, who did not develop contact with modern society and "civilization" and therefore had no influence to modify their millenary customs and ways of life.