As in other ancient civilisations, mathematics in India began in counting and drawing: numbers and plane geometry. The earliest textually recorded geometry is that of the Sulbasutra (around 800 BC onwards) which are manuals for the construction of Vedic altars, its mathematical high point being the `theorem of the diagonal’, Pythagoras’ theorem to you and me. I will state its earliest formulation and touch briefly on some of the ideas around it as found in the texts.