Samsara exists because of the craving, hatred & ignorance within our own mind.
Samsara includes all the 6 realms & the 31 planes of existence.
We are stuck in Samsara bcos we do not see our true mind. All sentient beings are constantly being reborn into higher or lower realms according to the good & evil thoughts in their own minds.
Where did it all began?
Samsara is like a ring. Does a ring has a beginning or end? The root cause of suffering is not lust or aversion, but Avijja (fundamental ignorance). From Avijja arises all defilements that forms the wheel of Samsara. If our true mind is the sun, then Avijja is the dark cloud that obscures the sun. Disperse the cloud with the wind of the Dhamma, & the sun will be able to shine on all things once more.
When enlightenement is reached, we shall realize that for something that wasn't really there in the first place, what is there to "cease to exist"; to enter extinction? Only then would we truly understand what "Samsara IS Nibbana" means! By now, all of us have seen the Israel-Lebanon conflict in the news. War is cruel & innocent people are dying. Scenes of the dead resemble that of the torments suffered in Hell. Where does all this suffering come from?
The Middle East is transformed into hell because of the hatred that clouds the minds of the Israelis & the Arabs. It is this inner hatred that leads to war, destruction & death. But if the mind is pure, then the Buddha-land is also pure. Always remember - Heaven & Hell is in the mind, so is Nibbana. I sincerely hope the people in that region can radiate Metta (loving-kindness) towards all sentient beings, friend & foe alike every day. Only in this way can they remain invulnerable to all harm amidst the fierce fighting, sadhu.