...if not, then who or what is governing these occurrences?
In the Diamond Sutta (see excerpt below) Buddha mentions the previous Buddha as being called Dīpankara Buddha possibly existing around ten thousand years ago. Then came Gautama Buddha and the next Buddha to occur could be Maitreya Buddha. Buddha also mentions here that there have been 84,000 multi-million Buddhas. I have no resistance about the existence of these Buddhas especially since losing the perception of chronological time, but when I observe sentient forms, there is - for the most part - some kind of growth or expansion of some sort happening with no real, tangible or perceivable force behind it.
With such a huge time span between the appearance of Buddhas it's perplexing to see this as either an evolutionary cosmological expansion of consciousness or... somebody somewhere sending in the forces in the same way that a declining school receives a new headmaster to try and rectify the mess.
Is anything regarding this mentioned in any of the major Buddhist schools of thought?
"Furthermore, Subhuti, if a son or daughter of good family, while reciting and practicing this sutra, is disdained or slandered, his or her misdeeds committed in past lives, including those that could bring about an evil destiny, will be eradicated, and he or she will attain the fruit of the most fulfilled, awakened mind. Subhuti, in ancient times before I met Buddha Dipankara, I had made offerings to and had been attendant of all 84,000 multi-millions of Buddhas. If someone is able to receive, recite, study, and practice this sutra in the last epoch, the happiness brought about by this virtuous act is hundreds of thousands times greater than that which I brought about in ancient times. In fact, such happiness cannot be conceived or compared with anything, even mathematically. Such happiness is immeasurable.
Apparently, there are 'ages' that have been defined...
Traditionally, this age [degeneration] is supposed to begin 2000 years after Gautama Buddha's passing and last for "10,000 years". The first two ages are the Age of Right Dharma followed by the Age of Semblance Dharma. During this degenerate third age, it is believed that people will be unable to attain enlightenment through the word of Sakyamuni Buddha, and society will become morally corrupt. In Buddhist thought, during the Age of Dharma Decline the teachings of the Buddha will still be correct, but people will no longer be capable of following them.