Samthô came into existence an unfathomable number of millenia ago. It was built off the remnants of the First Formations which themselves brought forth the first gods. We do not know, what these First Formations were exactly, but they seem to have been living beings as all worlds are said to be made from bones, blood, flesh and fibre.
Samthô has four general historical ages which are preceded by three prehistorical ages of unknown length. The historical ages commenced with a big catastrophe, the Great Flood, which started the first era or Era of the Water. It was followed by the second era, also called Era of the Trees. This was ended by another great catastrophe, a volcanic eruption called the Great Scorching. This brought about the third era, also known as the Era of the Fire. It was, until now, the shortest of the eras, lasting only 127 years after which the fourth and current era, the Era of the Earth started.
Every continent or larger region has developped it's individual view(s) on history, times and eras, so it is of little help to divide the general Samthô timeline into more specialised sections.