Shiva Trilogy Collection 3 Books Set By Amish Tripathi (The Immortals of Meluha, The Secret of The Nagas, The Oath of The Vayuputras):

The Immortals of Meluha:
1900 BC. In what modern Indians mistakenly call the Indus Valley Civilisation. The inhabitants of that period called it the land of Meluha. A near perfect empire created many centuries earlier by Lord Ram, one of the greatest monarchs that ever lived. This once proud empire and its Suryavanshi rulers face severe perils as its primary river, the revered Saraswati, is slowly drying to extinction. They also face devastating terrorist attacks from the east, the land of the Chandravanshis.

The Secret of The Nagas:
Today, He is a God.4000 years ago, He was just a man. The hunt is on. The sinister Naga warrior has killed his friend Brahaspati and now stalks his wife Sati. Shiva, the Tibetan immigrant who is the prophesied destroyer of evil, will not rest till he finds his demonic adversary. His vengeance and the path to evil will lead him to the door of the Nagas, the serpent people. Of that he is certain.

The Oath of The Vayuputras:
ONLY A GOD CAN STOP IT. Shiva is gathering his forces. He reaches the Naga capital, Panchavati, and Evil is finally revealed. The Neelkanth prepares for a holy war against his true enemy, a man whose name instils dread in the fiercest of warriors. India convulses under the onslaught of a series of brutal battles. It's a war for the very soul of the nation.