In Monty Python's Life of Brian there is a classic scene where the Jewish “terrorists” discuss their plans to “dismantle the entire apparatus of the Roman Imperialist State,” which, as the leader, Reg (played by John Cleese), says has “bled us white, the bastards. They've taken everything we had, and not just from us, from our fathers, and from our fathers’ fathers.”

But then the discussion quickly turns to what the Romans had actually given Palestine. Reg summarizes it as follows: “All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?”

Empires are obviously very complicated realities that invariably generate both boosters and critics. In the case of the Mongol empire, the last twenty-five years have witnessed a scholarly turn—one that coincidentally correlates well with the post–Cold War neoliberal agenda—that may be deemed as being on the booster side of the spectrum. Thus rather than perpetuating the age-old vision of the Mongols as being simply a mindless horde leaving unspeakable devastation in their wake, scholars have instead shown how the Mongols were not only fully cognizant of their operations, but, as such, the Pax Mongolica was also pivotal in integrating Eurasia and thereby played a role in shaping the early modern world. The pinnacle—or nadir (depending on whom you ask)—of such work was no doubt Jack Weatherford's 2004 New York Times bestseller Genghis Khan and the Making of the Modern World (New York: Crown).

Peter Jackson's awe-inspiring and monumental new work, The Mongols and the Islamic World, is an important corrective to these rose-tinted interpretations. And this is no doubt on account of two factors. The first is that the two overarching themes that animate the work are the impact of the conquest on the Muslim world, and the subsequent consequences of Mongol rule. Yet, even more important in shaping the book's narrative drive is the fact that “the vantage point of this book is largely that of the subject Muslim rather than the infidel master” (p. 6).

To this end Jackson holds no punches. He therefore reveals in exhaustive detail both the “shock and awe” and economic retardation that defined both the Mongol conquests and their subsequent rule. In fact, on account of the empire's early unity being quickly eclipsed by endless internecine Mongol warfare, he argues that the very idea of the Pax Mongolica should largely be jettisoned. Moreover, contrary to the much-ballyhooed cultural encounters that supposedly defined the empire, Jackson argues that these exchanges really had no lasting impact. For example, the well-known introduction of Chinese medicine and historiography into Iran during the Il-Khanate changed neither their Galenic medical practices nor subsequent Muslim historical writing.

So what actually were the impact and consequences of the Mongol empire? In answering these intertwined and inordinately complex questions, let me assure you that Jackson's argument—much less the material marshaled to make it—is far more sophisticated and nuanced than this cursory review can begin to convey. But essential to his approach is a keen awareness that both the Mongol conquests and their subsequent rule were never static realities. Thus the strategies, ideologies, and consequences of Chinggis Khan's seven-year campaign were invariably not the same as Hülegü’s sack of Baghdad in 1258. Nor were the Il-Khan's policies of the fourteenth century regarding taxes, agricultural policy, or relations with the local Muslim elite necessarily in tune with those of the Chaghatayid or Jochid uluses. Rather, on account of numerous factors, they all invariably evolved in multifarious ways for better or worse.

And it is precisely in making such moral judgments that Jackson is most careful. Thus whatever the issue may be—from the status of Muslim women in post-conquest Iran to the impact of the influx of Chinese silver on the West Asian market—he not only carefully surveys what all the sources tell us about the particular issue, but also queries why they tell us what they do. By so doing he therefore—perhaps inevitably—very often comes to the judicious conclusion that it is complicated.

Yet, in one regard there is no dispute. One consequence of the Mongol conquests was that all three of the western khanates converted to Islam, which subsequently expanded both the demographics and the territoriality of Islam in all those realms. But again, this expansion was not uniform either. In Iran, for example, Shi'ism came to dominate, while it was Sufism elsewhere. And as evidenced most famously in the work of Ibn Taymiyya, these developments had numerous ripple effects across the wider Muslim world. Thus, the Mongol conquests changed forever the world of Islam. But, if you truly want to understand how the Mongols did shape the history of Central Asia and the Middle East—and thereby played a fundamental role in shaping our world of today—you need to read Peter Jackson's magisterial book.