The Maurya Empire was a geographically extensive Iron Age historical power in ancient India, ruled by the Mauryan dynasty from 321 to 185 BC. Originating from the kingdom of Magadha in the Indo-Gangetic plains (modern Bihar, eastern Uttar Pradesh and Bengal) in the eastern side of the Indian subcontinent, the empire had its capital city at Pataliputra (modern Patna). The Empire was founded in 322 BC by Chandragupta Maurya, who had overthrown the Nanda Dynasty and rapidly expanded his power westwards across central and western India taking advantage of the disruptions of local powers in the wake of the withdrawal westward by Alexander the Great's Greek and Persian armies. By 320 BC the empire had fully occupied Northwestern India, defeating and conquering the satraps left by Alexander.

With an area of 5,000,000 km², it was one of the world's largest empires in its time, and the largest ever in the Indian subcontinent. At its greatest extent, the empire stretched to the north along the natural boundaries of the Himalayas, and to the east stretching into what is now Assam. To the west, it conquered beyond modern Pakistan, annexing Balochistan, south eastern parts of Iran and much of what is now Afghanistan, including the modern Herat and Kandahar provinces. The Empire was expanded into India's central and southern regions by the emperors Chandragupta and Bindusara, but it excluded a small portion of unexplored tribal and forested regions near Kalinga (modern Orissa), till it was conquered by Ashoka. Its decline began 60 years after Ashoka's rule ended, and it dissolved in 185 BC with the foundation of the Sunga Dynasty in Magadha.

Alexander III of Macedon (20/21 July 356 – 10/11 June 323 BC), commonly known as Alexander the Great (Greek: Ἀλέξανδρος ὁ Μέγας, Aléxandros ho Mégas from the Greek αλέξω alexo "to defend, help" + ανήρ aner "man"), was a king of Macedon, a state in northern ancient Greece. Born in Pella in 356 BC, Alexander was tutored by Aristotle until the age of 16. By the age of thirty, he had created one of the largest empires of the ancient world, stretching from the Ionian Sea to the Himalayas. He was undefeated in battle and is considered one of history's most successful commanders.

Alexander succeeded his father, Philip II of Macedon, to the throne in 336 BC after Philip was assassinated. Upon Philip's death, Alexander inherited a strong kingdom and an experienced army. He was awarded the generalship of Greece and used this authority to launch his father's military expansion plans. In 334 BC, he invaded Persian-ruled Asia Minor and began a series of campaigns that lasted ten years. Alexander broke the power of Persia in a series of decisive battles, most notably the battles of Issus and Gaugamela. He subsequently overthrew the Persian King Darius III and conquered the entirety of the Persian Empire. At that point, his empire stretched from the Adriatic Sea to the Indus River.