After the death of Alexander in 323 BC, many Greeks came to settle on the northern western boarders of India with Bactria (area to the north-west of the Hindukush mountains in the present day north Afghanistan) as an important centre.
The rulers of Bactria came to be called the Bactrian-Greeks because of their Hellenistic (Greek) ancestry.
One of the rulers of the line named Demetrius as mentioned above came into conflict with Pushyamitra.
However, the most celebrated Indo-Greek ruler was Menander. His empire appears to have included southern Afghanisthan and Gandhara, the region west of the R. Indus. He has been identified with king Milinda mentioned in the famous Buddhist text Milindapanho which contains philosophical questions that Milinda asked Nagasena (the Buddhist author of the text) and informs us that impressed by the answers, the king accepted Buddhism as his religion.
Menander is believed to have ruled between c. 155 BC and 130 BC.