The Nigerian jihadist movement Boko Haram has gone through a number of iterations since it emerged in the early 2000s. One major question about the group, from its early days until the present, has concerned the nature and the extent of its ties to other jihadist groups. Support from al-Qaida in the Islamic Maghreb may have been one enabling factor in Boko Haram’s campaign of sustained guerrilla violence starting in 2010. More recently, Boko Haram pledged allegiance to the Islamic State in March 2015, a tie that seems more rhetorical than operational, but that may contribute to flows of fighters and weapons between Nigeria, Libya, and elsewhere.

I have long treated Boko Haram as a primarily homegrown movement, but there is one international connection that stands out to me from Boko Haram’s early years, before its decisive turn to jihadism in 2010. That connection is the intellectual debt that Boko Haram’s founder, Muhammad Yusuf (1970-2009), owed to one of the world’s most influential Salafi-jihadi thinkers, the Jordan-based Abu Muhammad al-Maqdisi (b. 1959) There is no evidence that the two men ever met, and neither did Yusuf directly name al-Maqdisi in any writings or lectures that I have located. Yet there are two substantial pieces of evidence that al-Maqdisi’s writings were crucial to Yusuf as he articulated his own Salafi-jihadi creed in 2008-2009, the period just prior to Boko Haram’s mass uprising in July 2009.

First, Yusuf almost certainly borrowed ideas and citations from al-Maqdisi. As I describe in my recent book, Yusuf published a manifesto in 2009 entitled Hadhihi ‘Aqidatuna wa-Manhaj Da‘watina (This Is Our Creed and the Method of Our Preaching). Hadhihi ‘Aqidatuna overlaps with al-Maqdisi’s writings in several ways. For one thing, the book shares a title with one of al-Maqdisi’s works (entitled simply Hadhihi ‘Aqidatuna). Additionally, Yusuf’s manifesto adopts a similar rhetorical strategy to al-Maqdisi’s book. Both authors present the Salafi-jihadi creed as identical to mainstream Salafi thought and as completely continuous with the thought of figures such as Taqi al-Din Ahmad ibn Taymiyya (1263-1328), the medieval Damascene theologian.

Moreover, Yusuf writes at length about three themes that al-Maqdisi also treated, namely al-wala’ wa-l-bara’ (loyalty and disavowal), izhar al-din (manifesting religion), and the exemplary nature of the Prophet Ibrahim (Abraham). In Salafi-jihadi eyes, al-wala’ wa-l-bara’ involves exclusive loyalty to fellow Muslims and a stark disavowal of all other allegiances. Izhar al-din means adopting an outspoken, activist posture toward practicing and spreading Islam. Abraham, meanwhile, is for Salafi-jihadis an example of acting single-mindedly in the quest to manifest religion and disavow all non-monotheists, even one’s own family.

Finally – and here is where we see al-Maqdisi’s influence on Yusuf most clearly – Yusuf cites some of the same passages that al-Maqdisi cites from nineteenth-century Wahhabi hardliners. Two key nineteenth-century texts that both al-Maqdisi and Yusuf used were Hamad ibn Atiq’s Sabil al-Najat wa-l-Fakak (The Path of Salvation and Liberation) and the collection of Wahhabi writings called Al-Durar al-Saniyya fi al-Ajwiba al-Najdiyya (The Glittering Jewels of the Najdi Responses). Sometimes Yusuf’s citations are identical to al-Maqdisi’s, so that one suspects outright plagiarism from al-Maqdisi; in one edition, Al-Durar al-Saniyya runs to sixteen volumes, making it unlikely that Yusuf would have come to these citations entirely on his own. Yusuf must have had a copy – at the very least – of al-Maqdisi’s 1984 Millat Ibrahim wa-Da‘wat al-Anbiya’ wa-l-Mursalin (The Community/Creed of Abraham and the Call of the Prophets and the Messengers). It would have been easy to obtain a copy online, although perhaps it was given to Yusuf by an associate.

Why would Yusuf have downplayed the influence that al-Maqdisi had on his thinking? One answer may be that Yusuf was wavering about his commitment to jihadism up until the final months of his life, and that he still had some hopes of presenting himself as a mainstream Salafi scholar. Yusuf had begun his career within the mainstream Salafi fold in northern Nigeria – figures who rejected jihadism – and it was not until the mid-2000s that he fell out with his mentors and peers in the wider Salafi movement. Another possibility may be that Yusuf was keen to situate himself as the pre-eminent scholarly authority for his audiences. And so while it bolstered his intellectual authority to cite from nineteenth-century Wahhabis and from the twentieth-century Saudi Arabian religious establishment, it could have undermined his authority to be seen as the blind follower of a living Jordanian jihadist.

This brings us to the second piece of evidence that Yusuf was influenced by al-Maqdisi: even if Yusuf downplayed al-Maqdisi’s influence, Yusuf’s opponents within Nigeria’s Salafi movement linked Yusuf to al-Maqdisi in an attempt to discredit both men. Just a few months before Yusuf led Boko Haram in its mass uprising in July 2009, a major Nigerian Salafi scholar, Dr. Muhammad Sani Umar Rijiyar Lemo, came to Maiduguri, the epicenter of Boko Haram, to denounce Yusuf. Rijiyar Lemo, however, focused only indirectly on Yusuf – instead, he devoted his two-day lecture series to criticizing the global jihadist movement more broadly. In one significant passage, Rijiyar Lemo explicitly belittled al-Maqdisi’s credentials, denying al-Maqdisi the status of scholar. Rijiyar Lemo, a graduate of the Islamic University of Medina in Saudi Arabia, also positioned himself, rather than Yusuf, as the authority who could interpret Saudi and global Salafi scholarship.

What do the ties between Yusuf and al-Maqdisi tell us about Boko Haram? For one thing, they show how Yusuf was attempting to construct an intellectual architecture as Boko Haram drifted into jihadism. In the early and mid-2000s, even after some Boko Haram offshoots launched a disastrous uprising in 2003-2004, Yusuf was willing to operate within mainstream society: he served on a government committee, he interacted with politicians, and he even made statements (perhaps disingenuous, but a far cry from his later postures) indicating a tacit acceptance of the pluralistic, secular environment in which he found himself. By 2009, however, he was headed toward a collision with authorities. Al-Maqdisi’s ideas helped him to flesh out the justifications for that collision.

As noted above, Yusuf and al-Maqdisi almost certainly never met, but their intellectual tie connects Yusuf to a long genealogy of jihadist thinkers. That tie also connected Boko Haram to the Islamic State – in an ideological sense – even before Boko Haram pledged allegiance. Although al-Maqdisi has essentially rejected the Islamic State’s authority, many of the core ideas that he popularized were crucial for the Islamic State’s own intellectual framework. For example, Islamic State propagandists continue to cite ideas like the example of Abraham, albeit without crediting al-Maqdisi (see pp. 20-23 here). Given that Boko Haram and the Islamic State have a shared intellectual DNA, their convergence (again, likely much more at the rhetorical level than in any operational sense) should not be surprising.