After Alexander the Great the Greek Seleucid dynasty of Persia held on to the trans-Indus region. After Seleukos Nikator was defeated by Chandragupta Maurya in 303 BC, the trans-Indus region was transferred to the Mauryas. In mid third century BC the Seleucid rule ended. The Greeks of Bactria rose in revolt under the leadership of Diodotus. These Greeks were later known as Indo-Greeks when they gained a foot hold in the Indian sub-continent. Bactria situated between the HinduKush and the Oxus was a fertile region and it controlled the trade routes from Gandhara to the west. The Greek settlement in Bactria began in the 5th century BC when Persian emperors settled the Greek exiles in that area.
About the same time the Seleucid king defeated King Subhagasena after crossing the Hindu Kush in 206 BC. This defeat reveals the unguarded nature of north-western India. The son of Euthydemos, Demetrois conquered modern southern Afghanistan and the Makran area he also occupied some parts of Punjab. Then around 175 BC the homeland of Bactrians came to be ruled by Eukratides another branch of the Bactrians. His son Demetrios II penetrated deep into the Punjab proceeding along the Indus he penetrated till Kutch. The most known Indo-Greek was Menandar whose claim rests on the Buddhist treatise the questions of King Milinda discussions between Menandar and the Buddhist philosopher Nagasena and he ruled the Punjab from C 160 to 140 BC. Menandar not only stabilized his power but extended his frontiers. His coins are to be found in the region extending from Kabul to Mathura near Delhi. He attempted to conquer the Ganges Valley. Probably he was defeated by the Sungas. After Menandar Strabo ruled. At that time Bactria was ruled by a different group of Bactrian. Little later Antialkidas ruled from Taxila as known from the inscription from Besnagar near Bhilsa. This inscription was incised on the order of Heliodoros who was the envoy of Antialkidas in the court of Besnagar. Heliodoros got a monolithic column built in honour of Vasudeva. Thus began the Bhakti cult of Vasudeva. The penetration of Indo-Greeks as well as of Sakas, Pahlavas and Kushana influenced the government, society, religious literature and art of ancient India. Even before Indo-Greek rulers established themselves in India the services of the Greeks were utilized. Ashoka appointed a Greek as very viceroy of his province. After the Indo-Greek period a Greek during the period of Kushans was entrusted with engineering work.