Why do we still don't know exact birth & date year of the Buddha?

Question

I just want to know:
1)Why do we still don't know exact birth & date year of the Buddha?
2)What are the factors that is limiting in knowing Buddha's birth & death year?
3)Why many people/countries/traditions contradict? Many countries following different traditions, follow different Buddhist calendar year i.e. years since Buddha left.
4)Even the recent Nat Geo Excavations reveal he might be born in 6th Century B.C. A 2013 news which still doesn't official claim nor does it leave a convincing conclusion till date, on whether their findings are indeed perfect or not. Nor their findings seems to be accepted if its true.
5)Does the pali text gives any reference to the same?

Answer 1

Knowing the precise date of the Buddha's birth is not very useful knowledge within the Buddha's teaching, as it is presented in the Pali Suttas. How will knowing this precise birthday help any student transcend their own suffering? Only the most worldly and materialistic forces within any tradition would care about such superficial things.

The Pali Suttas(and arguably the Sanskrit Sutras) are the closest to what the Buddha actually taught. All traditions derive their truth from the Suttas/Sutras and other truths that might or might not be so compatible with the Buddha's actual original teaching. These additions were made for reasons of culture, politics and practicality IMHO.

If one wants to know what was likely the truth that the Buddha taught then one might stick to the core teachings that the Buddha repeated over and over again in the Suttas/Sutras.

It seems to me that these core teachings fit within themselves with great precision. Their potential is so awe inspiring to me that I wonder what, in 2500 years, has been stopping so much of humanity from embracing the Buddha's teaching or any teaching like the Buddha's teaching.-Metta :)

Answer 2

The story of the Buddha's life according to the Pali Canon can be found here. According to it, the Buddha lived for 80 years.

A chronology of the Buddha's life and Theravada Buddhism can be found here.

According to this Wikipedia page, Year 1 of the Buddhist Calendar started on 13 May 544 BCE according to the Burmese religious tradition and the 11 March 545 BCE according to the Thai religious tradition. Historical or archaeological dates for the Buddha's passing are around ±100 years from the traditional dates.

From here:

BE = Buddhist Era. Year 1 of the Buddhist Era calendar is the year of the Buddha's Parinibbana (death and final release), which occurred in the Buddha's eightieth year (480 BCE according to the "historical" timeline; 544 BCE by tradition).

The actual date of the Buddha's birth is unknown. According to Buddhist tradition, the Buddha's birth took place in 624 BCE, although some recent estimates place the Buddha's birth much later — perhaps as late as 448 BCE {1}. 560 BCE is one commonly accepted date for the Buddha's birth, and the "historical" date for that event that I adopt here.

Events in the timeline prior to -250 CE are shown with two CE dates: the date based on the "traditional" nativity of 624 BCE, followed by the date based on the "historical" date of 560 BCE. After -250 CE the "historical" date is dropped, since these dates are more appropriate only in discussions of earlier events.

To calculate the CE date corresponding to an event in the Buddhist traditional calendar, subtract 544 years from the BE date. The BE dates of well-documented historical events (particularly those in the twentieth century) may be off by one year, since the CE and BE calendars start their years on different months (January and May, respectively).

{1} The Buddhist Religion: A Historical Introduction (fourth edition) by R.H. Robinson & W.L. Johnson (Belmont, California: Wadsworth, 1996)