Brihadratha (IAST: Brihadratha Maurya) was the last ruler of the Maurya Empire. He ruled from c. 187 – c. 180 BCE. He was killed by his general, Pushyamitra Shunga, who went on to establish the Shunga Empire. Mauryan territories, centred on the capital of Pataliputra, had shrunk considerably from the time of Ashoka when Brihadratha came to the throne.
Brihadratha Maurya was killed in 180 BCE and power usurped by his general, Pushyamitra Shunga who then took over the throne and established the Shunga Empire. Bāṇabhaṭṭa's Harshacharita says that Pushyamitra, while parading the entire Mauryan army before Brihadratha on the pretext of showing him the strength of the army, crushed his master. Pushyamitra killed the former emperor in front of his military and established himself as the new ruler.
In 180 BCE, northwestern India (parts of modern day Afghanistan and Pakistan) was occupied by the Greco-Bactrian king Demetrius (Dharmamita), following the overthrow of the Mauryan dynasty by the general Pushyamitra Shunga. The Mauryans had diplomatic alliances with the Greeks, and they may have been considered as allies by the Greco-Bactrians. The Greco-Bactrians may also have invaded India in order to protect Greek populations in the subcontinent. He established his rule in the Kabul Valley and parts of the Punjab region. Soon, however, they had to leave for Bactria to fight a fierce battle (probably between Eucratides I and Demetrius).