Refer to a blog post by Malaysia's ex Prime Minister, Mahathir Mohammad:
Macron is not showing that he is civilised. He is very primitive in blaming the religion of Islam and Muslims for the killing of the
insulting school teacher. It is not in keeping with the teachings of
Islam. But irrespective of the religion professed, angry people kill.
The French in the course of their history has killed millions of people. Many were Muslims.
Muslims have a right to be angry and to kill millions of French people for the massacres of the past. But by and large the Muslims
have not applied the “eye for an eye” law. Muslims don’t. The French
shouldn’t. Instead the French should teach their people to respect
other people’s feelings.
My question is, did French really kill millions of Muslims?
*(Nitpickers might want to argue that this was not Mahathir's original meaning as he only said killed millions of people. Many were Muslims., but I would suggest that those who intend to argue along those lines read the two paragraphs in their entirety, if the French didn't kill millions of their brethren then Muslims certainly have no right to kill millions of French people in return)
It is hard to define where "the history of France" actually started. There was the realm of Francia since 481, the Kingdom of France since 987, experiments with different forms of republicanism and authoritarianism since 1789 until France finally arrived at its current form as a presidential democracy in 1958. So when one talks about "The French over the course of their history" then they might be referring to a timespan anywhere between 60 and 1500 years, depending on what narrative they want to push.
But if you are looking for historic atrocities committed by any European superpower (which isn't Germany), then a good place to start looking is usually the Colonial era. During that era, most European countries sailed all around the world to "civilize" less developed regions, which usually involved brutally murdering any locals who didn't want to be "civilized".
The French were pretty active during that period. The French colonial Empire conquered most of West-Africa, which had (and still has) quite a large Muslim population. And as with any "colonization", those conquests were often very bloody. France only renounced their claims on most of these countries in the 20th century.
Particularly notable is the French conquest of Algeria in 1832 where (depending on who does the estimation) between 500,000 and 1,000,000 Algerians lost their lives during the initial conquest. It is not clear how many Algerian Muslims were victims of crimes against humanity under French rule, as estimates vary widely depending on the political agenda of who makes the estimation. But some sources like Turkish government controlled news estimate several millions. Algeria did not gain independence from France until 1962, and only after fighting another war for it where the military and civilian casualties again went into the hundreds of thousands.
So if Mahathir Mohammad referred to the colonial history of France, then his claim might indeed be true. In what way French people of today should be held responsible for things which happened during colonialism is a matter of debate.
There has been a recent political agenda by Turkey's government to expose French violence in Algeria as Genocide, in response to France's recognition of the Armenian genocide. Consequently, English and Arabic sources like Wikipedia may contain major propaganda injections, like that quote of 10 million from Andulu Agency government news agency.
Muslim-French combat goes back to the year 713, in the Muslim invasion of Europe, when the Muslims sent a reconnaissance mission across the Pyrenees, and fought the provinces of southern France, the kingdom of the Visigoths.
Many thousands of Southern Visigoths were killed and enslaved until the Battle of Poitiers in 732, where 12,000 Muslims were killed by the Franks, and their forces were annihilated from France by Charles Martel.
That was a 50 year war. The Moors fought for another 700 years in Spain, giving a death toll of 7-10 million, including French involvement for the Reconquista.
Muslim invasion of Europe and North Africa cost 15 million lives.
Napoleon's wars killed 5 million, including 65,000 Egyptians and Syrians.
French colonialism killed 2 million, many Muslim.
The Mongol invasion which killed 30-40 million.
France's next engagement in the Muslim world was for The Crusades, which recaptured southern Europe and tried to get to Jerusalem, and eventually failed and destroyed the Christian empires of Anatolia (Turkey). (See history of Turkey). The death toll of The Crusades was about 2 million lives.
The southern coasts of Europe were poor, empty, and constantly raided for centuries, and the Italians, Spanish and French were not able to stop the slave raids until the invasion of Algeria in 1830 when French cannon technology was powerful enough to destroy the ramparts of Algiers.
After that, France expanded into Africa, using natives for work-camps to enrich the French Empire. There was a famine and cholera epidemic in 1866 which killed 500,000 Algerians. The most violent was the Algerian war of independence. Some sources inflate the deathtolls into the millions, but in-depth research of demographic pyramids and Algerian government records is lower, i.e. 350,000 deaths, including 30,000 Francophile Algerians killed after Independence, and Egyptian, Syrian, Moroccan and Tunisian Mujaheddin who had enrolled in the Algerien liberation army. source. There were atrocities on both sides.
There isn't major evidence for a government extermination program of many thousands or millions of Algerians, like it is alleged for the Turkish genocide of Armenians, Although a million Algerians of fighting age were forcibly displaced into remote camps in 1961 to prevent them from joining the army of independence.
In Algeria, the local and colonist civilians mixed, traded, worked and were paid, went to school together, the cities and villages were safe, there was relative peace. The war of conquest saw fierce Algerian tribesmen in their thousands wielding knives and muskets, and corresponding deathtolls, and famine, and the death toll is contentious and unknown, and had no human rights charter on either side, which made them especially bitter and bloody. The war of independence was provoqued by French Fascism, it was industrial.: Academic sources forward figures 350,000 combatants and civilians, including mujaheddin from training bases in Tunisia and morocco for mujahaddin from as far away as Syria and Egypt, and Algerians fighting on the french side. Turkey suggests 10 million people were killed, and academic studies suggest about 500,000 Algerians were assassinated in 130 years of colonialism, excluding the famine and epidemic.
In WW2, the French conscripted Africans and Algerians to fight the Germans. The Algerians violently rebelled after WW2, and France violently quelled the rebellions. When Britain and Holland were arranging independence for their colonies, France was still fighting their colonies.