Rainforests provide another place of refuge for those seeking to escape – or a base from which raiders can operate. The Amazon, the Central African rainforest, and in the forests of Southeast Asia (especially Borneo/Kalimantan), are all home to vastly diverse populations of people living in what can be an unforgiving environment. Some of these cultivated a fearsome reputation as well as a skill in managing the alliances and rivalries of the time – the Tamoio people of the Amazon, for instance, organized themselves into a loose confederacy and fought against Portuguese colonial powers (selectively allying themselves with other European powers), just as groups like the Karen of highland Burma allied with the British against the lowland Burmese. Some of these groups increased their reputation by displaying the heads of their enemies – the Bugkalot of the Philippines and Dayaks of Indonesia both took heads, and the famous "shrunken heads" of the Amazon were actually de-boned and mummified heads made by Achuar and other groups.

When we think of the military capability of rainforest groups, we might think of blowguns (Amazon), crossbows (Southeast Asia), and spears (everywhere), and lightly-armored soldiers on foot. But they also had tanks: elephants. Elephants’ soft feet make little damage to the forest floor, they are able to move through thick cover relatively easily, and their height allows them to forge swollen jungle streams. In 20th century warfare, the Kachin of Burma used (and use) elephants to great effect against the Burmese army. While the treads and tires of Burmese army vehicles were bogged down in muddy ground, Kachin elephants could pass in relative silence, enabling them to outflank and outmaneuver their supposedly better-armed opponents.