Hiking equipment
According to Tom Brown, the basic plan for survival is in the order of shelter (including clothing), water, fire, and food. Cody Lundin writes about the "Rule of 3s"; this relates to human survival without basics: three minutes without air, three hours without shelter, three days without water, or three weeks without food.
Tanka people
Some Chinese myths claim that animals were the ancestors of the Barbarians, including the Tanka people. Some ancient Chinese sources claimed that water snakes were the ancestors of the Tanka, saying that they could last for three days in the water, without breathing air.