Origin: Buddhist Mythology, Indian Mythology
Originally, Apalala was a man named Gangi. He used subtle charms to restrain the power of the wicked dragons in the region so that they could not afflict the crops with violent storms.  His work enabled the people to produce abundance, and in return, each family paid him a tribute. However, after many years passed, many forgot or refused to pay the tribute, and Gangi became wrathful. He prayed that he might transform into a dragon to afflict them with storms and destroy their crops himself. 
At the end of his life, Gangi was reborn  as a terrifying water serpent or dragon  of that country.  In his new incarnation as Apalala, he raised hailstorms and floods so that he could feast upon the crops of the fields.  The flowing source of the river emitted a white stream that devastated all the products of the earth. 
The Buddha, moved with pity for the plight of the people, descended supernaturally that he might convert the violent dragon Apalala  and tame him.  Vajrapani, Buddha's companion, took up a thunderbolt, and  smote the mountainside where Apalala lived. 
The dragon-king Apalala came forth, terrified, and paid reverence to the Buddha. He listened as the Buddha preached the law, and his heart became pure as his faith awakened.  After his conversion,  the Buddha forbade him to ravage the crops. Apalala thanked him for the sacred instruction, but he feared for his own survival.  He said, "All my sustenance comes from the fields of men."  Without his storms and floods, he would starve. Thus, he asked the Buddha to allow him a single gathering every twelve years. Out of compassion, the Buddha permitted this. That is why, once every twelve years, calamity results from the overflow of the White River. 
Apalala was reborn as a Naga, which can take the form of a man but usually has the lower body of a serpent and the upper body of a human.
- Apalala was once a man named Gangi. 
- In wrath, Gangi prayed that he might be transformed into a dragon to devastate the land that had forgotten his good work. 
- When he died, Gangi was reborn as Apalala of the Swat River, or the White River. 
- The Buddha converted and so tamed Apalala. 
- Apalala had the power to start hailstorms and flood the river. 
For more information on footnotes and references, please see the bibliography.