Long ago, the gods and the asuras wanted the nectar of immortality, which lay hidden deep in the Ocean of Milk. The only way to bring it up was to churn the whole sea — a task far too great for either side alone.
So they used a mountain as the churning-stick and a great serpent as the rope, and both sides pulled together, back and forth, for ages and ages.
Up came wonderful treasures — and finally the nectar itself. Even those who did not like each other achieved the impossible by pulling together.