Answer:
what led to the division of Islam into Sunni and Shia was the conflict over who should be the caliph
Explanation:
After the death of prophet Mohammed some followers of Mohammed and the religion of Islam that he founded believed that a CALIPH ( a successor or next line ) should be determined by the populace of the Muslim community while some followers believed that the CALIPH should be a member of prophet Mohammed family and this was the main event that led to the division of Islam into Sunni and Shia.
Although they still believe in almost all core Muslim values and beliefs.
