To bring to the mind’s eye the monks and hermits of the Thai Forest Tradition, see The Thai Buddhist Forest, Thudong: Forest Monks and Hermits of Thailand. It is a quite beautiful, wordless slideshow with an excellent musical soundtrack (1:10:20).
From Thudong: Forest Monks and Hermits of Southeast Asia, we are told
. . . wandering elders or masters with one or two disciples or younger monks, might take up a months-long regimen of travel, sometimes without a particular itinerary, following rivers, forest highlights, mountains, valleys, and the thread of isolated villages for their food, though sometimes wandering monks went without food for days when they lost their way. Such monks could readily pursue the practices of sleeping in the open air under trees and in caves or in cemeteries, all the while adhering to a discipline of meditating in the wilderness.
And meditation was, indeed, the core of their practice, in vivid contrast to the pundit monks. One observer summarizes the motivation of the ascetic monks thusly:
They knew that if they studied the dhamma without practicing it, they would remain unaware of its deeper meaning. They realized that the value of the dhamma was not to be found in reading and studying but in training the mind through the thudong life. Finally, they understood that the best place to study the Buddha’s teachings was not in a comfortable monastery but in their own school, their own university: the heart of the forest, a grove, the shade of a single tree, the cemetery, the open air, the slope of a mountain, the foot of a mountain, a valley. They believed that such places were recommended by the Buddha as the supreme university.
For more information about the thudong tradition, watch the Ajahn Siripanyo video, Dhutanga: Spirit of Thudong (47:02). (It is but one of 19 videos documenting an Ajahn Chah Remembrance Day celebration in Malaysia, commemorating the 20th anniversary of the passing of Ajahn Chah on January 16, 1992.)
There is also an excellent extended article on the subject by Bhikkhu Khantipalo entitled, With Robes and Bowl, Glimpses of the Thudong Bhikkhu Life.