What is "upulvan"

Upulvan is a guardian deity of Sri Lanka. Sri Lankan Buddhists believe him also as a protector of the Buddhism in the country. The name Upulvan depicts his body colour which means "blue water lily coloured". The cult of Upulvan started during the medieval period in Sri Lanka and later the deity was identified with the god Vishnu (Vishnu deviyo) of the Hindu tradition. According to the local lore and legend, Upulvan is the god whom the Lord Buddha entrusted with the guardianship of Sri Lanka and Buddha Śāsana of the country.