There is absolutely no record of a 3600 year orbit regarding Nibiru and no mention of Nibiru when speaking of this time frame. The 3600 year periods that are mentioned within the Babylonian writings are a Babylonian designation for time within their mathematics, called a "Sar" (if you look it up yourself it takes you to a specific reference regarding the following:), it actually pertains most often, to the length of time their "ancient rulers lived and reigned" - type it in and you will see for your self.
There were no records of devastation regarding Nibiru, as Sitchin claimed occured "in the heavens" - within the writings of the Enuma Elish it speaks of Tiamat and Anu and various others who Sitchin supposes are planets when in fact they were actually people or "entities" of some sort, whether human, human/angel hybrid or angel I do not know, it goes back to the Antedeluvian Sumerian Kings list which is their list of Kings they worshipped as gods that lived before the flood - The mighty men of old, men of renown spoken of in the Bible in Genesis 6.
First of all....3600 years is too cute...it will not be the same all the time.....
Check this book out for more research
Catastrophe: An Investigation into the Origins of Modern Civilization."
Yes Ken.... I am a good student.