Orientalism is an institutional activity from the West that studies the Eastern world in fields such as religion, language, science, thought, art, and history and produces value judgments about the East. Those who are engaged in this work are orientalists. Orientalists have closely examined Islamic civilization and its sources by going into the field and have produced many works. However, their attitude to get familiar with Eastern Islamic society was based on their superiority and the denigration of Islamic civilization. They made groundless claims against the most crucial source for Muslims, the Holy Qurʾān and hadiths. One of these orientalists was the Italian Leona Caetani. His work Annali Dell'Islām, which he wrote from an Orientalist point of view, was considered by Westerners as a school book in Islamic history and was accepted as a reference work in its field. This work, translated into Ottoman by Hüseyin Cahit Yalçın, caused great resentment and anger among the intellectuals of the Republic of Turkey at the time and led to the writing of refutations. The massacre of Ka'b Ashraf, which took place in the third year of the Hijrah, in Caetani's History of Islam, has always been a debate in Islamic history. With the spread of the Prophethood in Arabia, different balances emerged, and with the migration from Mecca to Medina, this situation took on another aspect. The new religion could not get used to the change in the balances in Medina, and the Jews, who could not digest this situation, embarked on hostile activities to humiliate the Prophet and Islam. One of these people was the Jewish poet Ka'b b. Ashraf, did his best to reveal his enmity to the Prophet Muhammad and Muslims on this path leading to his murder. His enmity, which peaked with the victory of the Muslims in the Badr War, increased even more, and the defeat of the polytheists, whom he called "the ruler of mankind", aroused great sadness in him. He went to the city of Mecca with his entourage, saying, "If Muhammad really killed so many people, the earth is better than the earth above it". He wrote poems to arouse the people there and to keep their pain even more vivid. Caetani, in his History of Islam, expressed what a dangerous and disturbing enemy Ka'b b. Ashraf was by saying that when he returned to Medina, he made violent attacks on the Prophet and the new religion, and even tried to seduce Muslim women, in other words, he did everything possible to earn the Prophet's most hatred and to become a man who angered him the most. In the face of such a dangerous enemy, the Prophet asked his companions, "Who can save me from the speech of Ka'b b. Ashraf? Because he disturbs Allah and His Messenger". Thereupon, Muhammad b. Maslama accepted this job. Together with Ka'b's milk brother Abu Nailah b. Salamah, Abbad b. Bishr, Haris b. Aws and Abu Abs, made a plan to eliminate Ka'b b. Ashraf slaughtered him—the killing of Ka'b b. Ashraf took place for various reasons and was not a selfish and unlawful killing. The background of this event with its causes and consequences in the historical process should be thoroughly analyzed, and inference should be made without focusing on the arbitrariness of the killing of Ka'b b. Ashraf. Caetani, who makes anti-Islamic discourses on many subjects and does not hesitate to express his opinion when necessary, did not make a counter-discourse on the massacre of Ka'b b. Ashraf in his History of Islam. In our study, we will evaluate Caetani's views by centering them.