Question

why do the interior of the deccan plateau and east of the sahyadri receive low rainfall?

Answer 1

Here is your answer -

It is because the Deccan plateau and east of the shaydri

Lie in rain shadow regions

Answer 2

The interior of the deccan plateau and the east of the sahyadri are part of the Western Ghats in India and they receive low rainfall because they lie in the rain shadow region.

A rain shadow region is area which is covered by the mountains thus blocking the rain bearing clouds to pass and stops rainfall.