re: Avtar in Hinduism?
King Asoka was strong enough to promote and spread Buddhism across India. This period last for 4 centuries. In those four centuries the region became vegetarian (as this was preached by Budha) and as we see different depiction of Budhas life in form of sculpture, etc at Taxila, Hinduism got influence to make murtis during that era. As per some historians, before Buddha there were no murtis of Hindu Gods and first temples in India were of Buddhism.
Interestingly, one of the most influential religious personality of India (Buddha) has been portrayed as negative avtar of Vishnu, who came to spread evil and Vishnu will now appear as tenth avtar in the form of Kalki avtar to eradicate these evils. It is rather interesting that this tenth avtar Kalki has been connected with Prophet Muhammad (SAW) by some scholars.