Indian History
Guptan Empire
In 319 AD, the king Chandragupta II (the second) managed to unite all of northern India into a great empire again. (He was not related to the first Chandragupta, but he wanted people to think he was). Even some of the south was brought under Guptan power. The Gupta kings were not Buddhists but Hindus, following the older Indian religion.

Gold coin of Chandragupta
II
But in 455 AD the Huns invaded India from the north and destroyed the Guptan Empire. After that, India was split into small kingdoms again until the Muslim invasions around 1000 AD.