Final answer:
The split between Sunni and Shia intensified during the 1450-1750 time period due to the official declaration of Shia Islam as the state religion of Persia, the Safavid dynasty's conversion efforts, and the military rivalry between the Safavids and the Sunni Ottoman Empire.
Step-by-step explanation:
The split between Sunni and Shia intensified during the 1450-1750 time period for several reasons:
- The official declaration of Shia Islam as the state religion of Persia (now Iran) in the early 16th century created a division between the Shia-majority Iran and its mostly Sunni neighbors.
- The Safavid dynasty's conversion efforts in the Islamic world brought tensions between Sunni and Shia to a level not seen since Muhammad's death, leading to increased hostilities.
- The military rivalry between the Safavids and the Sunni Ottoman Empire further exacerbated the split between Sunni and Shia.