There are cycles in history. However to find these cycles you need to start from data that was compiled by people who didn't know about the cycles. An Encyclopaedia is a good source. Then using all the data you have to find a way to categorize events in to various classes, again without biased picking. So that should be done by someone expert in the field and who does not know about the cycles. Finally you can then look for cycles in that resulting data using mathematical tools like Fourier analysis.

You might find the work of Raymond Wheeler interesting. He made a thing called "The Big Book" which is basically an analysis of history for several thousand years with what was going on in science, architecture, music etc etc. He found that a lot of things came back to long term weather fluctuations - wet/dry, hot/cold. Whether leaders were regarded as great, mediocre or rotten was almost totally determined by the weather. Seems the leader gets credit for when the crops are good or bad even though it was nature. I see the same things happening today. There is a book about Wheeler's work called something like "A Roadmap of Time" and the author's name starts with Z but I can't remember it .. Zuhartov or like that.