The Mauryan Empire
According to the obscure history books, a man named Chandragupta Maurya was the Indian equivalent to Alexander the Great. By the age of 20, he put the bulk of India under his rule, and after Alexander’s death, prevented his Macedonian generals from invading India.
This empire lasted from 322-187 B.C. until a coup left India divided, weak, and open to an invasion from the Greeks.