In the beginning only the pawns positions are fixed. Withe starts by dropping a piece in its starting area somewhere behind the pawns. Then black drops and so on until all pieces are on the board. After all pieces are on the board, no more pieces will be dropped and normal playing starts.
The movement of the Elephant differs from the Bishop in Chess in that it moves like the Knight but one field more diagonally.
The Queen or General moves only one field diagonal.
Pawns do not promote.

 
This is what I believe to be more or less the original form of Chess or Chaturanga, after studying and reading a lot about this topic. The only thing I was sure was the movement of the Elephant - which however is only preserved in Korean Chess (Janggi).
However it is very likely that the rules of the original game were not fixed as concerning promotion of pawns, movement of the elephant and starting positions and a lot of things might be done by agreement.
Maybe the stronger player got weaker movements of the elephants and and the weaker player got his pawns placed on more advanced positions on the board. The reason why I kept this Burmese starting position is that Thai Chess and Shatranj progresses very slow and the Burmese starting positions seems to be the most advanced.
Because promotion does not occur in Chinese and Korean chess and is also missing in Shatranj I have not included it.