Apalala is a water dragon from Buddhist legend.
Apalala was said to live at the source of the Swat river and was converted to Buddhism by Buddha. After his conversion, he aided the prosperity of the area by making sure it rained. The tale is often told to Buddhist children for them to learn their happiness lies in their faith.
Buddha and Apalala (Hsuan-tsang Version)
The 'Ta fang hsi-yu chi' by Hsuan-tsang (a Chinese scholar who wrote about India) tells the story of Apalala. Kasyapa Buddha was a man with the power to control the weather. He did so by controlling the evil dragons that might bring storms. In return, the local people offered him grain. The people started to forget to offer the grain and Kasyapa grew angry. He prayed that he would become a dragon, so that he could punish them.
This was granted. After his death he became the dragon Apalala and made his home in a pond in Udhyana (an old name for the area of the Swat valley). He destroyed the area with storms and rain. This continued until Sakyamuni Buddha visited the area. He persuaded Apalala that what he was doing was wrong. They came to an agreement where Apalala would stop his destruction in return for one crop every twelve years. Rather than relying on the people to provide the offering, he would take it himself by flooding the land.