Ali was the Rashidun caliph who died around 21 Ramadan 40 AH. Ali ibn Abi Talib, Muhammad’s cousin and son-in-law, became the fourth Rashidun caliph in 656 CE and governed from Kufa until his death in 661 CE.
The date is sometimes expressed with a small distinction. A Kharijite assassin struck Ali with a poisoned sword during the dawn prayer on 19 Ramadan; Ali died from his wounds roughly two days later, commonly recorded as 21 Ramadan 40 AH. Some historical summaries give the corresponding Gregorian date as 28 January 661.
Ali is also central to the Sunni–Shia historical divide. Sunnis recognize him as the fourth Rashidun caliph, while Shiites regard him as the first imam and a key successor to Muhammad. The other three options—Abu Bakr, Umar, and Uthman—were the preceding Rashidun caliphs.