Lange's A Sudanic Chronicle: The Borno Expeditions of Idrīs Alauma (1564–1576) is an indispensable work. A scholarly, modern translation of one of the chronicles of imam Ahmad b. Furtu, it is one of the earliest extant West African chronicles, written in 1576. It is also one of the most detailed primary sources from Borno on the Sayfawa dynasty and the reign of Idris b. Ali. Indeed, when paired with the 1578 chronicle on the Kanem campaigns of Idris b. Ali against the Bulala on the opposite shore of Lake Chad, Ahmad b. Furtu is probably our most important written source on Kanem-Borno from the precolonial era. Unfortunately, the chronicler only covers the first twelve years of his ruler's reign, but he provides an intimate look at some of the social, political, demographic, military, diplomatic, religious and economic dynamics in 16th century Borno. Moreover, Lange's scholarly translation is more accurate and usable than the 19th century Redhouse translations or the Palmer ones with their egregious errors. For that reason alone, plus the detailed footnotes by an academic who specializes in the region, Lange's translation is required reading.
What stands out more clearly in this translation than that of Redhouse is the literary allusions, Quranic references, and the role of military tactics. For instance, the expertise in which Idris, the brother of Vizier Kursu organizes the musketeers, shieldsmen, and cavalry to effectively defeat Ngizim towns was far more explicit here. The greater precision and contextual knowledge of the translator vividly brings to life some of the combat, military strategies, and long-term goals of Idris Alooma to wear down, defeat, displace, destroy, and starve rebels, external enemies, and nomadic foes (like the Tuareg of Air). Snippets of the population movements and displacements, such as the construction of ribats to end "pagan" incursions, are additional evidence of large-scale movements across Borno which reveal the long-term strategy of the Sayfawa to consolidate their power. Furthermore, Ahmad b. Furtu's individuality and background as the chief imam of Birni Gazargamo are more readily discernible here, perhaps due to useful footnotes of Lange.
Unfortunately, Lange never followed this with a similar scholarly translation of the second chronicle of Ahmad b. Furtu. It's a shame since the two chronicles, both panegyric in tone and clearly meant to flatter the sultan, nonetheless constitute hugely significant sources on events in Kanem and Borno during the late 16th century. The Kanem campaigns described by Ahmad b. Furtu are essential for highlighting the larger regional ambitions, influence, and extent of Sayfawa power across the Central Sudan. It also would have been interesting to read a similar gazetteer of towns and settlements in Kanem as well as Lange's commentary to shed light on the Quranic, literary, or linguistic peculiarities of the text.