The Maurya Empire, also known as the Mauryan Empire, was a geographically extensive Iron Age historical power in ancient India, ruled by the Maurya dynasty from 322–185 BCE. Originating from the kingdom of Magadha in the Indo-Gangetic Plain (modern Bihar, eastern Uttar Pradesh) in the eastern side of the Indian subcontinent, the empire had its capital city at Pataliputra (modern Patna). The Empire was founded in 322 BCE by Chandragupta Maurya, who had overthrown the Nanda Dynasty and rapidly expanded his power westwards across central and western India, alongside Chanakya's help, taking advantage of the disruptions of local powers in the wake of the withdrawal westward by Alexander the Great's armies. By 316 BCE the empire had fully occupied Northwestern India, defeating and conquering the satraps left by Alexander. Chandragupta then defeated the invasion led by Seleucus I, a Macedonian general from Alexander's army, gaining additional territory west of the Indus River.