Once upon a time before the Philippines was discovered by Ferdinand Magellan. A beautiful place where mountain hills, river, sea shores and water can be seen in that time. The seashore is at the foot of the mountain and hills.

The early civilization started life in upland and high level above the sea and along river banks. Time passed and due to erosion of the mountain, soils cover the seashores, the plain land grows bigger and wider. The seashores were now far from the mountains as it was used to be.

Agusan River (got its name from the word "AGUS" which means "flow of water") is one of the longest river in the Philippines during that time. The river gently flows in the foot of the mountains. People are using the river as their means of transport and communication. They uses the river for delivering and trade their crops to the mainland. Most people who travel along the river, they always pass a narrow part of the river which they find very difficult to navigate because of a big formation of rock that is blocking the river. Thus, this place was locally know as "PIT-OS" which means "Narrow or Difficult". "Pit-os was then called "Bit-Os".

The civilization in the main land was growing and the place was known to be the Trading Capital of Asia. Many merchants from China and other places brought their products for barter and trading with the natives which also trades goods like gold and their crops.

Sadly, Agusan River happened to be in a volcanic fault line. By the time there was a massive earthquake, the rock formation which was known as "Pit-Os" was shaked and fell down to the river and blocks the narrow creek which most people used as their passage to the main land. Due to the earthquake,  the Agusan River system was rerouted and the old narrow creek was gone. This happened when people heard a loud explosion due to the erosion of the rock formation along the narrow creek known as "Pit-Os".

Because of what happened to "Pit-Os", most of the traders were stranded and cannot find ways back to the sea. Thus, that loud explosion heard was the origin of which Butuan got its name.

During the early part of 1970, many artifacts were found from digged ancient boats at Libertad, the place were most of the traders were stranded during the time when the narrow creek called "Pit-Os" was block due to the explosion cause by a massive earthquake. These boats were called Balangay which happens to be a trademark for Butuan's rich culture and history. 

* The rock formation that block the river during the earthquake was called Bit-Os Moon Rock, this name was given by the person who discovered it, Ramon P. Carampatana. Archaeologists said that the rock was 2 million years in existence.