Question

What were two main causes of the bitter rivalry between the Ottoman and Safavid empires?

Answer 1

The Safavid and Ottoman dynasties were both of Turkish ethnicity. The Safavid empire extended from the Caucasia ( Armenia, Azeribijan, etc.) to India, Iraq, the Persian Gulf, and parts of central Asia and the Caspian Sea.The Ottoman empire, on the other hand, ruled the the rest of the Islamic empire (Middle East, Balkans, and North Africa).

The Ottoman empire was older and stronger than the young Safavid empire, but the Ottomans were alarmed as the Safavid strength and influence grew and felt their interest was threatened. Moreover, the Safavid followed Shia Islam, while the Ottoman people were followers of Sunni/Sufi Islam.

But the main reasons for the conflict are rather political than for sectarian religious factors as many try to force this idea of Sunni/Shia conflict.

Answer 2

https://en.wikipedia.org/wiki/Ottoman%E2%80%93Safavid_War_(1623%E2%80%9339)