When the Aryans occupied the Indian subcontinent, they brought with them three things that the bronze-age Indus Valley Civilisation did not have. They rode horses, they used iron and most importantly, they had the Vedas. These books of knowledge were passed down orally for generations, until the advent of the Sanskrit script. The fourth book - the Atharvaveda which includes the Vastu Shastras - was compiled when the semi-nomadic Aryans gradually began to settle into an agrarian way of life.

With the passage of time, the early settlements coagulated into larger villages and then towns. It was probably at this stage that the Vastu Shastras were incorporated into the Atharvaveda Veda, so as to provide uniformity in the overall scheme of things. The people in those days - unlike our modern urban populace - built their own dwellings. No contractor, engineer or architect was required. Their home was a simple affair of timber frame, wattle or mud-brick walls and a thatched roof. The Vastu code provided a basis for growth to take place in a less haphazard way.

The Shastras advised the potential house-builder on everything, right from choosing the site, to getting the correct consistency of mud for plastering the walls. It taught what kind of soil would bear the load of the home and how to find the cardinal directions. Besides, the whole gamut of mantras and pujas associated with the process of building were included.

The Gnomonic Compass
This is how the solar north was charted before the advent of the magnetic compass. A "gnomon" or pole was erected in the middle of the site and a circle of radius equal to the height of the pole drawn in the ground around it. Then its shadow was plotted at sunrise (point 'A') and sunset (point 'B') to give the east-west axis. After that it was a matter of simple geometry to draw parallel and perpendicular lines to arrive at the cardinal directions.

During the early Vedic period, the Vastu Shastras were flexible and allowed for variations based on individual requirement and local conditions. During the later Vedic period, however, they crystallised into a set of hard and fast rules known only to the pandits and sthapatis - mason architects. That was when the obfuscation began...