The charge that Islam was an import to Africa did show up among Nation of Islam’s (NOI) critics. Kwame Ture (at the time known as Stokely Carmichael) of the Black Panthers charged that “Islam is not an African religion,” and argued Islamic expansion was linked to the slave trade. NOI members rebutted this in different ways. The most common way was to argue on the basis of NOI’s cosmology that Islam actually predated Muhammad and was connected with the creation of the Black people.
Nation of Islam’s Creation Story
The Nation of Islam’s (NOI) version of Islamic history differs quite dramatically from most historians' or popular understandings of Islamic history. NOI understood Islam to be the original religion of humanity from the beginning of time 66 trillion years ago and original humans to be Black. According to NOI’s understanding, Black people had brought Islam to the Middle East, not the other way around.
According to the teachings of Elijah Mohammad, the founder of NOI, the first people were Arabic speaking Black Muslims of the Tribe of Shabazz. Earth was originally a utopia governed by a council of 24 Black Muslim scientists. This paradise was lost when an evil scientist named Yacub created white people out of experiments on the Black race. White people were understood to be devils. Islam’s origins according to NOI were not actually in the Middle East or connected with Muhammad.
Defending Islam as a Black religion
In 1971 Edward L.X. Truitt spoke out against Carmichael’s claim that Islam was not an African religion by contending that “Islam is the religion of the Original people, who are Black, brown, red, and yellow descendants of the original Black Man, the maker and owner of planet earth.” Thus, Islam was actually the creation of Black people. Embracing Islam for Black people was seen as a restoration of a lost heritage.
Other NOI members argued that the any effort to portray Islam as foreign to Africa was a plot to undermine NOI and Elijah Muhammad. Diogenes X. Grassal, for example, denounced any contemporary focus on African culture as a plan by white people to undermine Black men. According to Grassal, Yoruba and Swahili were inferior languages to Arabic, and Islam was the source of all Black achievement in Egypt, Arabia, Asia, and West Africa. Charles 67X denounced Black nationalists like Amiri Baraka for contending Arab Muslims had harmed Africa. 67X maintained that Islam had brought advanced civilization to Africa. NOI members often took harshly critical views towards Africa, which they believed to be primitive without the teachings of Islam.
NOI and Moorish Science
I have previously written on AskHistorians about the NOI’s roots in the earlier Moorish Science Temple, an Islamic movement which appeared in Chicago after World War I. Like the later NOI movement, Moorish Science, was not grounded in traditional Sunni or Shia understandings of Islam or deeply concerned with the historical particulars of Islam, Muhammad, or early Islamic history in the Middle East. Both movements instead claimed that Islam was racially connected with Black Americans.
Summary
NOI’s understanding of Islam’s origins, teachings, and spread, had little to do with secular or mainstream Islamic understandings of history. For NOI, Islam was not a Middle Eastern religion, it was a Black religion, which had been associated with Black people since human beings had existed. Debates about Islamic expansion and involvement in the slave trade did not matter to NOI’s sense of sacred history.
Sources consulted:
Curtis IV, Edward. Black Muslim Religion in the Nation of Islam, 1960-1975 Chapel Hill, NC: University of North Carolina Press, 2006, particularly 89-91.
Gardell, Mattias. In the Name of Elijah Muhammad: Louis Farrakhan and the Nation of Islam. Durham, NC: Duke University Press, 1996.
GhaneaBassiri, Kambiz. A History of Islam in America: From the New World to the New World Order. New York: Cambridge University Press, 2010.
Marable, Manning. Malcolm X: A Life of Reinvention. New York: Viking, 2011.
Note: Fixed a few spelling and technical errors.
While you wait for an answer specific to your question, you may be interested in these answers by u/Commustar which explore aspects of Islam's history in sub-Saharan Africa.
I strongly suspect that the question is phrased as it is with deliberately tendentious intent, but I want to underscore something that comes up in u/Commustar's linked answer elsewhere in this thread.
u/USReligionScholar does a fantastic job of looking at how this question came up within the Nation of Islam and how some of the Nation's critics also raised the point, but it's also important to understand that for much of sub-Saharan Africa, Islam's spread was not a consequence of military conquest by Arab-speaking armies during the initial rise of Islam. That characterization holds for North Africa and for some portions of the Red Sea-adjacent region of northeast Africa, but not for coastal East Africa or for Senegambia and the upper and middle Niger (nor other parts of West Africa a bit later on). The spread of Islam in these regions was gradual and largely associated with trade and with the arrival of Islamic scholars to major urban centers and the courts of large dynastic states in the case of West Africa. In West Africa especially, Islam was originally a courtly religion associated with rulers (who often practiced some form of religious pluralism, representing both indigenous and Islamic traditions). When so-called "jihad" revolutions broke out between 1600 and 1900 in West Africa, these were entirely indigenous and involved no troops or forces from outside the region.
/u/USReligionScholar has mentioned the criticisms that were actually levelled against the NoI, and /u/swarthmoreburke explained the nature of Islam's entry into West Africa, so I'll try to answer the final part of your question: why Islam?
In sum, one can point to at least three distinct but related reasons a unique national-religious community formed around Islam within the African diaspora; first, the long history of Islam in West Africa, particularly Senegambia, from where a considerable percentage of slaves were taken, and the endurance of this community's lifeways; second, the association of Islam with an authentically African, non-creole heritage which could serve as a new national/racial identity around which to coalesce, and which was particularly attractive as 'Asiatic'; third, the association of Islam broadly with anti-colonial movements and Third Way politics, which saw it positioned as one of the chief opponents to the recognized injustice of white supremacy.
First, I would like to emphasize that, not only was Islam not brought by conquerors, it was not "foreign," despite whatever criticisms may have been levelled at the Nation of Islam by its detractors. Such a position is only defensible in an absolutely technical sense, insofar as Islam was literally borne of a region outside the continent of Africa. But Islam is as foreign to Africa as Christianity is to Europe; that is, both are Asian religions which were thoroughly adopted by large segments of populations well outside their place of origin, and this was to such an extent and over such an extended period of time as to render any designation of "foreignness" essentially meaningless. West African Muslims, who have existed as such for over a thousand years, and certainly those Muslims who formed the African diaspora (who were not numerically insignificant) did not regard their religion as "foreign" or other. Sylviane A. Diouf, in her detailed study of the lived experiences of enslaved West African Muslims in the Americas (who continued to practice their faith in a variety of ways, sometimes under quite severe pressure), argues that:
[ . . . ] contrary to what is sometimes asserted, Islam was not superficially implanted in West Africa. It was deeply rooted and for that reason could withstand deportation. During slavery, on both sides of the Atlantic, Africans were devout Muslims, sincere believers, strict practitioners, and active agents in the development and shaping of their religious and cultural world. [ . . . ] Islam was diffused not by outsiders (except in the early years) but by indigenous traders, clerics, and rulers. These carriers of the faith were natives and therefore identified culturally and socially as well as ethnically with the potential converts. [ . . . ] Africans themselves considered Islam an African religion. (Diouf, 98.)
Having established that, though, onto the key question: why adopt Islam (and, relatedly, why object to Christianity?)
While the evidence is not particularly forthcoming and unambiguous, there is some reason to believe that the Islamic lifeways of West African slaves, which persisted up until the late 19th century, influenced the practices of the Nation of Islam and the similar groups which preceded it. For example, prayer three times a day is a suspected American import from West Africa, where it is customary. More persuasively, "Sufism was not unknown among Africans and their descendants in North America, and vestiges of the lifestyle may have played some formative role in the reemergence of Islam in the early twentieth century [ . . . ] incontrovertible evidence for a substantial Muslim presence in antebellum North America, in combination with what is certain about the West African context, allows for responsible and plausible speculation, if tentative and not yet fully verifiable." Thus, Gomez observes that "Noble Drew Ali [the founder of Moorish Science, which predated and influenced the NoI], whose personal lineage may indeed include African Muslims, came out of a southern region connected to the core of the African Muslim community, and he grew up during a time when the memory and legacy of those Muslims was strong and vibrant. It may be that Sufism assisted in creating a conceptualization of life and its interior significations." (248) It's also perhaps interesting to note in this context that though the Nation of Islam is today highly unorthodox, it is arguably not more so than some other Sufi orders that have existed throughout Islamic history.
Beyond the obvious possible continuities that existed between communities, we should analyze the way this imagined community was constructed by, and played out in, the lived experienced of West Africans. In particular, there are three things which we might say generally characterized West African Muslim slaves in the colonial period (a) they were often already broadly familiar with Christian teachings and scripture and accustomed to regarding it as hostile to and mutually exclusive with their own beliefs, thus making conversion unlikely; (b) the Muslim inhabitants of West Africa had comparably high rates of literacy and erudition; and (c) their shared religious sensibilities and obligations meant that they were not as isolated by ethnic and linguistic divisions in diasporic communities as were those who followed more localized pantheons. As a result of these and other factors, Muslims "strove to remain outside of, not mix with, the cultural and religious models imposed by the West and Christianity [ . . . ] They chose to keep their previous frames of reference and values, and in so doing, they made it evident that neither the Christian world nor a creolized identity and culture appealed to them. " (Diouf, 142.)
The African-Islamic identity therefore in some sense constituted an alternative to the negotiation of one's identity through creolization. By situating oneself within an Islamic heritage, African-Americans could root themselves in a tradition which was parallel to, not a consequence of, the European system; a creed that could not be made to accomodate or incorporate Christianity, but definitionally ran parallel to it. In light of this, "Islam was also a galvanizing force [ . . . ] [that could] even [instill or strengthen] a feeling of superiority over the “Christian and kafir dogs.” Muslims certainly thought that their religion was morally far above any other." (Diouf, 231)
It was this imprecise, 'creole' identity which the 20th century revival of African-American Islam sought to address. The search for religion, therefore, cannot be separated from the search for racial or national identity which so distressed many diasporic communities. Indeed, writers, such as Noble Drew Ali below, were very explicit about their desire to shed the generic identity thrust upon them in the Americas for one more grounded in a non-Western social reality:
the nationality of the Moors was taken away from them in 1774 and the word negro, black and colored, was given [ . . . ] The “Negro,” as they were called in this nation, have no nation to which they might look with pride. Their history starts with the close of the Civil War or more properly with his being forced to serve someone else. Thus he is separated from the illustrious history of his forefathers who were the founders of the first civilization of the Old World. This matter should be looked into with a hope of correcting it. (retrieved from Gomez, 224)
Perhaps the reason these concerns became especially exigent in the early 20th century, while earlier they could be ignored, was that the situation of Africans globally was now dimmer than ever. This was the case both internationally, where white supremacy had achieved unprecedented control over the world and seemed only to be growing, and within America, where even two generations after slavery the position of black folk within the body politic and the nation evidently remained an open question, with terrorism a regular occurence.
Equally as important, questions of identity and national belonging began to take on an existential gravity in the context of post-WW1 global relations.
Thus, the solution was a "configuration [which] relocated the source of an immutable black identity to Africa and away from North America while simultaneously erecting a transnational family to which blacks belonged," relying on "an economy of language in which there is the strong intimation of inherent and unresolvable racial polarities that are both expressed and sanctioned in religion." (Gomez, 274) Indeed, as early as 1887, Edward Wilmot Blyden (sometimes regarded as the father of Pan-Africanism), wrote in his book Christianity, Islam and the Negro Race that Islam “belong to a cognate race,” whereas Christianity “has followed chiefly the migrations and settlements of members of the Aryan race.” (264; 277-83, retrieved from Gomez) Such sentiments were echoed in The New Negro Movement more generally; Hubert Harrison, one of its most prominent figures, published an article entitled “The Negro Conservative: Christianity Still Enslaves the Minds of Those Whose Bodies It Long Held Bound.”
The impulse to inextricably tie nationality and faith was not unique to the Moors or the Nation of Islam - notably, this same tendency, when combined with a patent antipathy for Christian-Europe and a thoroughgoing search for an authentic alternative identity, likewise resulted in the emergence of "black Judaism" and the Abyssinian Movement as contemporary phenomenons. Of these, however, the Islamic movements remained by far the most popular.