The prehistoric Amazon had low numbers of hunter-gatherers due to poor soil and harsh landscape conditions, due to which it was not able to support advanced cultures. The arrival of Christian missionaries, oil companies, and farmers changed the lifestyle of a specific portion of the population, although some indigenous groups still avoid contact with the outside world. Missionaries stimulated changes in the indigenous medical-religious-political systems. In the Peruvian Amazon, the local government is too weak to carry out the usual functions of the state, and therefore oil companies have replaced the state in terms of various functions such as employment, building wells for the drinking water, healthcare, donation of electric generators, and aircraft transport of local indigenous authorities to meetings in Iquitos or Lima. The policies of the national government are turning the Peruvian Amazon into a productive area and are exploiting its natural raw materials. In modernising the Amazon region, however, the world is permanently and irreparably losing valuable knowledge regarding the nature of tropical areas.