Many Buddhist devotees don't know who are the five Buddhas and many only know about the current Buddha.
A Buddha isn't God or a person who can change nature in the way he wants. Buddhas are the persons who have make merit, from learning in revolution for long time ago. He was like us in the begining, but with all his brave he pray to help other people like the Buddha at that time. His pray lead him to perform meritorious acts through his lifes.
Five
Buddhas
At the beginning he would learn what is right what is wrong and he also punished in unpleasant places from his devil acts, but finally he knows what is right or wrong. Then he will perform more serious meritorious acts, even sacrifice his life for other people, which is Giving. there are other 9 meritorious acts, for example precepts, kindness, being not bias, diligence, patient, etc which he protect or perform even his life will be end.
The time is long as 10, 20, and 40 Gappa depends on his will. 1 Gappa is a long time as can explain with this: there is a hole that well made 16 Km Square,(9.94 miles), and 16 Km deep, and every 100 years, drop a yeast grain in it. Keep being like that until it's full. Last Buddha was the one who made merit for 20 Gappa.
This world had 5 Buddhas and the last one will the the kind of Buddha that make merit for 40 Gappa. Buddha who enlighten by the meditation, decide to teach people to practise and follow him to Nippana, (Nirvana=where that contain spirit who's without Adhamma which is Greed, Anger, and Delusion) He found Dhamma, which are the performing that brigh us to , No greed, No anger, and Enlightenment. Dhamma is the main of Buddhism, is the fact to bring people to pleasant sites.
Dhamma always exists even no Buddha. For example, kindness, diligence, evaluation, determination, precept (no bothering others), giving, etc. Dhamma is what we can touch in our mind, it's in the perfect shape of universe that we can really see. But that's for the person who practise until they have the mind that delicate enough to see. Buddha brought those dhamma to make people admire toward dhamma, and once Buddha tought those people with meditation, the enlighten and see through all what he tought.
A power of meditation that help people bored in revolution is remembering past lifes. But the most powerful thing from it is to know how to escape the revolution. Everyone must help oneself. But It's really the fact that make here we are right now. meditation of somebody is like a project of an expermation. And they always glad even just to stop their mind in peace.