Chaturanga

A small number of literary references seem to confirm the existence of chess by the beginning of the seventh century.

Islamic accounts, beginning in the ninth century, and Indian accounts from much later appear to indicate that chess was invented in India.

Chess scholars have made a plausible reconstruction of this ancient Indian game of chess, known as chaturanga.

The word chaturanga is Sanskrit and means four-limbed.

This term was first used to describe ancient Indian armies that were considered four-limbed for having corps of horses (cavalry), elephants, chariots, and footsoldiers. 

The pieces of a chaturanga set represented these four elements of an army.

A rajah and his minister were included on the board to command these forces.

The power of move of each piece was determined by the relative power of the army corp that it represented.

For instance, a chariot can move to many more squares than an elephant or a footsoldier.

The way a piece moves also suggests the manner in which its corp moved.

A chariot moves in straight lines.

A horse's (knight's) move might symbolize the way a rider attacks from a horse, forward to left or right but not straight ahead.

The movements of the rajah, minister, horse, chariot, and footsoldier appear to have been fixed early in the development of chaturanga.

The move of the elephant is less certain. 

At least three different elephant moves were tried in chaturanga.

The two square diagonal leaping move was probably the first tried, and it is the one that passed west to become the standard move until it was replaced by the move of the modern bishop.

H.J.R. Murray believed that the Indians may have felt the two square diagonal move an inadequate representation of the elephant's worth in the Indian army.   
As a result, the Indians tried different elephant moves in an attempt to find a better representation.

One Arabic author, al-Adli, wrote that the Indians played with an elephant that leapt two squares in either a vertical or horizontal direction.

Al-Adli's elephant could move to twice as many squares as the diagonal leaping elephant.

Al-Adli also wrote that the elephant was placed on the corners of the board and the chariots were placed in the normal elephant spot next to the rajah and minister. 

Another Islamic author, al-Beruni, described an elephant that had the powers of the minister with an additional forward move.

Al-Beruni's elephant could reach every square on the board.

H.J.R. Murray wrote that its five-fold move fit well with the Indian idea that the elephant was a five-limbed animal, the trunk counting as a hand.  

Murray also noted that this move was tried later than the other two elephant moves and that it was associated with Buddhist areas of India.  

The disappearance of the move may have been associated with the overthrow of Buddhism in India.