Revolt of the Samnites
The Samnites were a native New Greek tribe. Inland, there were few New Greeks. However, the city-state of New Athens was expanding inward toward Samnite territory. This led to the Samnites rebelling in 295 BCE. It was stopped by 275 BCE. However, this had caused racism and all Greek states were working hard to stamp out native culture.
Second Punic War
The Greek states allied together to combat Carthage in 264 BCE. However, this was a stalemate until 220 BCE. In this period, Hannibal, a Punic commander, used tactics to crush Greek forces in 216 BCE. This is what turned the tide of war in Carthage's favor. By 205 BCE, the Greek city-states signed a peace treaty in which almost all of Iberia except for a tiny enclave was given to Carthage. Considering he crossed the Alps with elephants, it is no wonder Carthage won.
The prosperity of Bharat (India) under the Maurya shocked the ancient world. However, the new emperor Bindusara began a period of good relations between Persia and Bharat. The annexed parts of Persia became more and more Bharati, with Buddhists eventually comprising a large minority.
However, a small kingdom known as Kalinga proved to be a thorn in Bharat's chest. This small kingdom refused to be part of Bharat. In return, a massive blockade of Kalinga was done. This ultimately failed, as Kalinga, although poor, survived although large parts of it were annexed by Bharat.
South of Hindustan, there were three Tamil kingdoms. Two of these were annexed by Bharat after gradual "chipping" of their territory eventually opened the path for invasion. The last one slowly fell under Indian influence
Ashoka was at first a cruel ruler, but after annexing Kalinga, he saw the devastation the blockade had caused. He became Buddhist. Buddhism spread around the world because of him. Buddhists in the last independent Tamil state overthrew the ruler and joined Bharat while Lanka fell under Bharati influence. This unified Bharat set in a period of peace as more and more people became Buddhist. Under this, Southeast Asia also fell under Bharati influence, forever changing Southeast Asia.