Explanation:

- Option 1: Religious differences

The Vedic Age communities generally practiced similar forms of religion. Their conflicts were not mainly based on religious differences.

- Option 2: Caste rivalries

The rigid caste system emerged later. In the early Vedic period, society was more grouped around tribes than castes.

- Option 3: Territorial expansions

While tribes fought for land, these battles were more connected to tribal identity and survival rather than systematic expansion as later kingdoms did.

- Option 4: Tribal conflicts 

Correct Answer: Most wars in the Vedic Age were due to conflicts between tribes competing for land, cattle, and resources.