I suggest you have a look at the material on the Vasudeva - Samkarsana iconography within the pancaratra system of 3rd - 2nd century BC.   This covers also some early Naga imagery, the earliest being aligned with Balarama iconography. Independent naga images are somewhat later. Some of the yaksas and yaksi sculptures are arguably Mauryan, certainly post-Mauryan (sorry for lack of diacritics... writing this on my phone). 

My 2004 Artibus Asiae  article (updated in my 2007 book, Buddhist Landscapes in Central India, British Academy) provides detailed discussion and bibliography for the above.

https://www.academia.edu/6618122/Naga_sculptures_in_Sanchi_s_archaeological_landscape_Buddhism_Vaisnavism_and_local_agricultural_cults_in_central_India_first_century_BCE_to_fifth_century_CE_2004_

Naga sculptures in Sanchi’s archaeological landscape: Buddhism, Vaisnavism and local agricultural cults in central India, first century BCE to fifth century CE (2004) www.academia.edu Naga sculptures in Sanchi’s archaeological landscape: Buddhism, Vaisnavism and local agricultural cults in central India, first century BCE to fifth century CE (2004)

And of course there is the enormous assemblage of terracotta deities, as studied recently for example by Naman Ahuja, not to mention the even larger and more poorly understood iconographies embodied in early Indian rock art (see Neumayer for example).

Best wishes

Julia