The Rlangs clan played an essential role in the religious and political history of the Tibetan central regions of dBus and gTsang between the twelfth and seventeenth centuries. Medieval Rule in Tibet presents an extensive and rich reconstruction of the trajectory of the family throughout this time, from its mythical ancestry to its ascent as the ruling power over vast areas, through its troubled succession disputes until its eventual decline.

The first chapter of the book consists of a study of the clan's genealogical account, the Po ti bse ru, a difficult and composite text probably finalized in the early fifteenth century, which functioned as a narrative of origins and as a family chronicle at the same time. Chapters 2–7 present the history of the family in a chronological fashion, divided by century. The first two chapters (12th–13th c.) are devoted to the foundation and rise of the main monastic seat controlled by the clan, namely gDan sa mthil – and the associated branch of the bKa' brgyud school, the Phag mo gru pa – offering new information on the institution's early history and its relationship to the religious and political powers of the time.

Chapter 4 (14th c.) is dedicated to the towering figure of Byang chub rgyal mtshan (1302–64), who succeeded in establishing the Rlangs as the rulers of great parts of Central Tibet at the end of the so-called Yuan-Sa skya rule. This chapter is based mainly on another extraordinary document, composed by the family leader himself, his so-called “testament” (bka' chems). The clan's control over the territory from their seat at sNe gdong was ensured by a mixture of military campaigns, marriage alliances, and diplomatic relationships with other noble families. The following chapters reconstruct these negotiations, battles and strategies in great detail, even year-by-year when possible, showing how dynamic, intricate, and rapidly changing were the political circumstances during the fifteenth to seventeenth centuries. The Rlangs-Phag mo gru remained nominally in charge for over two centuries, endowed with enormous prestige, although machinations at court, internal disputes, and military campaigns greatly threatened and at times eclipsed their actual dominion. Hence, the book retraces also the fortunes of competing powers such as the Rin spungs pa, based in gTsang, detailing the vicissitudes of their strongmen, describing the varying extent of their territorial reach, and relating their influence at the royal palace. This complex period of Tibetan history is made the object of systematic study for the first time in this book, and Czaja's exhaustive account constitutes a formidable resource for any further study on the subject.

His work draws from a great number of literary sources, mainly chronicles, biographies and epistles. They are complemented by fieldwork, photographs dating from the beginning of the twentieth century, and art historical evidence, with a special focus on the main familial monastic seat of gDan sa mthil. To the art of this religious establishment is devoted the eighth and final chapter of the book, which includes, in particular, the study of the iconographic programme of the memorial stūpas erected over time at the site. The amount of research work and data collected for this book is truly impressive, and it is made available to the reader in the lengthy footnotes and appendices, as well as in the hundreds of figures and plates that fill the entire second volume. Moreover, Olaf Czaja curated the exhibition “Golden Visions of Densatil: A Tibetan Buddhist Monastery”, gathering some of the stunning pieces that he had patiently traced from public and private collections while working on the book (Feb. 19–May 18 2014, Asia Society Museum, New York). The catalogue includes an introduction to the foundation and the history of the monastery, excerpts from the travelogues of Sarat Chandra Das and Giuseppe Tucci, and descriptions of the selected works. Regrettably, it was unavailable for purchase outside of the USA and readily sold out: it is currently out of print.

With such a wide scope of research and extensive source materials, a major issue is their organization and presentation to the reader: there is no one wholly satisfactory way of doing this. As mentioned above, the first and last chapters of Medieval Rule in Tibet pertain to issues of cultural history, respectively dedicated to the textual and visual self-representations constructed by the clan. However, there is no obvious break or differentiation between these sections and the core part of the book devoted to political history, nor are they effectively brought together, showing how the mythical, genealogical, religious, artistic, and political discourses interact and overlap. The difference in genre and context of production of the textual sources employed throughout the book is not highlighted, and – with the exception of the Rlangs po ti bse ru treated in chapter 1 – the corpus produced by the family (the bKa’ chems with its addenda and the chronicle Mig ’byed ’od stong) is not treated as bearing distinct qualitative features. Chapters 2 to 7 are divided by century rather than reflecting a periodization based on an overarching historical narrative recognizing major shifts in the family's fortune, as offered in the brief introduction. In order not to break the chronological flow of the narrative, complex issues or points of contention are treated in long footnotes that may discourage the negligent reader, who would miss a remarkable display of erudition and informed analyses of fascinating topics. A notable example is n. 54, pp. 223–5 on the controversial circumstances that led to the foundation of the monastery of bKra shis lhun po, which would be the dGe lugs pa outpost in gTsang throughout the Phag mo gru rule. In this and many other instances, the voice of the historian is itself relegated to the footnotes, discussing contrasting accounts, evaluating the import of specific events, or pointing to historical relationships and developments.

This rich, engaging, and thoroughly researched book demands from the reader the effort of following its author through the thousands of folios and hundreds of images that constitute its backbone: this process is rewarding in itself, offering many hidden stories, secondary pathways to explore, and precious references to anyone interested in the political, religious, and art history of Tibet. With so much of the material and literary legacy of the Rlangs Phag mo gru pa lost and scattered, these volumes offer a compelling insight into their monastic enclave and ruling policies. As the major study of fifteenth-seventeenth-century Tibetan history that has appeared so far, Medieval Rule in Tibet takes its rightful place in the series of the Austrian Academy of Sciences beside a number of publications that have quickly become reference works.