About 250 B.C. Diodotus (Theodotus), governor of Bactria under the Seleucidae, declared his independence, and commenced the history of the Greco-Bactrian dynasties, which succumbed to Parthian and nomadic movements about 126 B.C. After this came a Buddhist era which has left its traces in the gigantic sculptures at Bamian and the rock-cut topes of Haibak.
There are the remains of many other topes (or stupas) in the neighbourhood.
There is an obvious development from the serpent qua reptile to the deity or the devil, and that the original theriomorphic form is not at once forgotten can be seen in Zeus Meilichios, Aesculapius Amynos, in the Cretan snake-goddesses, or in the Buddhist topes illustrated by Fergusson.
The evidence from modern India can be supplemented by the medieval and ancient Indian sources, and, in particular, by the representations of the adoration of snake-deities on the Buddhist topes of Sanchi and Amravati.