Alexander died without any sons old enough to rule, and so his kingdom was split up among his generals. These generals, known as the Diadochi, squabbled amongst themselves over who was the rightful heir to the throne. They engaged in a series of conflicts known as the Wars of the Diadochi.
Lysimachus was one of the generals, who conquered Asia Minor, Thrace and later Macedonia, and accumulated vast riches. However, he was later defeated by Seleucus. Seleucus was a young soldier who had risen through the ranks of Alexander’s army. He was the Governor of Babylon, but was forced to flee. He later became an admiral in the navy of Ptolemy I.
Antigonous was the first of the Diadochi to openly declare him a king. His ambition was to reunite the empire of Alexander by defeating all the other Diadochi rulers. This caused the remaining Diadochi to join together against him. They finally defeated Antigonous.
In this power struggle, none of the Diadochi, or their successors was ever able to unite Alexander’s Empire. However, they prudently promoted the intermingling of Greeks with the local peoples, leading to a fusion of East with West. This period is known as the Hellenistic Age.