Look at the Wikipedia article I linked above. Apparently, it's a cycle of eight years. The Javanese calendar has other such periods.
dates 2 is getting too boring! I can't skip a level because my answers get rejected because I miss out a word e.g. How many years "are" in one windu? please make it more interesting. I don't want to be failed by nit picky english issues. For me you can miss out the "are" and everyone will understand.