The Samsaric Cycle has No Beginning...

The Blessed Buddha once explained the round of existence as this:
No first beginning of ignorance can be perceived, bhikkhus, before
which there was no ignorance, and after which ignorance had emerged.
Nevertheless ignorance has its specific causal conditions:
When there is mental fermentation, ignorance also comes into being.
When the 5 mental hindrances are present, ignorance grows & expands.
AN V 113, MN I 54

No first beginning of craving for becoming can ever be perceived,
before which there was no craving for becoming, and after which
craving for becoming had emerged.
Nevertheless craving for becoming has its specific causal condition:
When there is ignorance of the 4 truths, craving for becoming arises.
AN V 116

But why does the Blessed One give this exposition of the round with
those two things as starting points? Because they are the outstanding
causes of kammic action that leads to the happy and unhappy destinies!
Ignorance is prime cause of behaviour, that results in unhappy destiny.
Vism 525

Naturally: In no cyclic process can a beginning ever be pointed out...
Why not? There is neither beginning nor end of a fully closed circle!

For explanation of this wheel of becoming click here:
http://www.vimokkha.com/paticcasamuppada.html

More on these prime causes of the round (vatta)  of being:
http://What-Buddha-Said.net/drops/II/The_Causes_of_Ignorance.htm
http://What-Buddha-Said.net/drops/II/The_5_Mental_Hindrances.htm
http://What-Buddha-Said.net/drops/II/The_Three_Fermentations.htm
http://What-Buddha-Said.net/library/DPPN/wtb/u_v/vatta.htm
http://What-Buddha-Said.net/drops/II/What_is_Ignorance.htm

No First Beginning!