Nats are human spirits worshipped by the local Bamar people long before the founding of the Bagan Empire.
Nats were all once human beings who have met with violent deaths and who were later worshipped and declared as guardians of the home, forests, villages and almost every aspect of daily life.
Even though they are spirits, Nats have human weaknesses like desire, wants and needs.
To the followers of Theravada Buddhism, Nat worship is therefore considered derogatory and immoral.
During the reign of the first King Anawrahta of the Bagan Empire, he wanted to create a Budhhist kingdom, having himself just converted to Buddhism.
He tired to destroy all Nat shrines in the kingdom and banished all Hindu images to a desecrated Vishnu temple known as the Monastery of Prisoner Nat.
However, so strong was the belief and practice of Nat worship amongst the local Burmese people that many took their worship underground, rebuilding small Nat shrines in their homes.
King Anawrahta, realising that he was actually turning the people away from Buddhism, rescinded the ban and allowed the people to continue with their worship.
During that time, Mount Popa, an extinct volcano 65 kilometres ways from the Ayeyarwaddy River was already the revered home of 36 Nat spirits.
The King added the 37th called Thagyamin, who is the Hindu deity Indra.
He then crowned Thagyamin as the King of the Nats. The Burmese people were then allowed to continue with their practice of Nat worship.
Effectively the King had made Nat worship subordinate to Buddhism. The staunch Buddhists pay no attention to Nats even though there are Nat statues in many Buddhist temples.
The present generation of Burmese people especially those staying in the urban areas are showing a declining interest and belief in Nat worship.
However, Mount Popa remains as the abode of the Nats and is fast regaining its importance in Burmese culture and beliefs, mainly due to the large influx of local devotees and foreign tourists.
At night the temple on top of Mount Popa lights up.