This small booklet represents the outcome of a lecture the author gave at the Berlin-Brandenburgische Akademie der Wissenschaften to an audience who probably were not experts in the field of maritime exchange during the medieval period. The lecture covered a broad spectrum of topics: it ranged from the years 1000 to 1500 with an emphasis on the fifteenth century, and covered the Indian Ocean from the Japanese shores to the Persian Gulf and the Red Sea. The author readily admits that it would be impudent to try to cover even the major incidents in a small booklet as presented, especially as many basic problems are not yet resolved. Philippe Beaujard's monumental recent work on the history of the Indian Ocean (Les Mondes de l'Océan Indien, 2 vols, Paris, 2012) is an affirmation on these difficulties.

In the initial section “Zum Thema” [About the topic], Ptak outlines some principal observations on his theoretical foundation without overstressing this part of his research. He basically adopts the concepts of Fernand Braudel and places himself in the middle of the sea in a boat with a view of the surrounding land. Accordingly, he distinguishes between historians sitting in such boats and the “landlubbers”. Ptak thus claims to ignore the hinterland largely and regards history as a longue durée phenomenon. This runs the risk of exclusively structuralist research which neglects diachronic developments. Nevertheless, it may be helpful to fix a profile board first, before getting into more specific research, especially when dealing with topics such as “Maritime Silk Road”, “History of the Indian Ocean”, “Exchanges in the Indian Ocean area” and so on. Thus the first chapter is entitled “Spaces and routes” (Räume und Routen) and tries to outline the spaces according to the views of historians of the different regions which, however, also depend on time. Thus, the common conception of a region called “Southeast Asia”, which even developed into an academic discipline, is rather recent and cannot be found in texts of the Song or Yuan dynasties (pp. 4–5). Maritime spaces were (and are) certainly interrelated with maritime routes – defined by the necessities of navigation with sailing vessels – and it may be difficult to respond to the question if concepts like a “maritime silk road” – the title of the short chapter two – did exist during the Middle Ages. If we look to the western side of the Indian Ocean we will find a great deal of research on the vast field of Middle Eastern geography and cartography which, however, is not discussed in Ptak's booklet. On the eastern side, we have the so-called “Zheng He map”. This map stretches from Nanjing to Hormuz and can thus be seen as a “maritime silk road map”, but it may be still difficult to judge from this map the geographical conception of the early Ming period. Did the Chinese at that time have in mind a “maritime” route stretching from the then-capital of China to the secluded island at the entrance of the Persian Gulf? This map shows a host of interesting features, some of them discussed by Ptak and also illustrated by good copies of parts of the map. The often spread bon mot about “Silk Roads” can be easily certified on Zheng He's map: we find there one northern and one southern route around Sumatra to the area of modern Bandar Aceh (pp. 13–14).

The next two chapters deal with natural features of the Indian Ocean area, such as volcanos, siltation (rather prominent in shaping the geographical features of the Pearl River delta during the last centuries), currents, flora and fauna. Ptak concludes his few explanations with the assumption that rather than “industrial” products such as silks, ceramics, and so on, animals and plants were the major commodities in Indian Ocean trade (p. 26). However, where shall we place then the Nanhai yihao 南海一号 vessel with its cargo of tens of thousands of dishes?

The following chapters return to political and economic factors. Ptak asks if the exchange was peaceful and orientated towards economy, and questions several established perceptions such as the turn from a peaceful “Indian Ocean society” towards a martial colonialization of this sea by the Portuguese. He refutes such a Chinese–Portuguese rivalry as well as colonial endeavours of the Chinese. To argue China is a threat rather fits Anglophone sorrows (p. 27). When looking at Indian Ocean history, one moves easily on to more recent waterways, thus later on the “one belt one road” initiative is mentioned, and Ptak rightly recalls the destiny of the natives of the Chagos islands elsewhere in his booklet (p. 31).

Ptak also questions material profit as the sole incentive of the travels on the Indian Ocean, again, he includes the “Estado da Índia” in his considerations, but details also the spread of Mazu, patron of the seafarers, and writes a bit about the role of Islam – we should certainly keep in mind that the country with the largest Muslim population is today found in Southeast Asia. Zheng He, the Chinese admiral, marks the end of the booklet, and several geographical and political aspects of his expeditions are discussed.

The final discussion is again focused on China, which wishes for a peaceful exchange in this region, in contrast to the Dutch and British in former, and the Americans in recent times (p. 51) and stimulates a “maritime culture” (haiyang wenhua 海洋文化), obviously in the wake of the “one belt one road” initiative. One can find announcements for a national contest of “maritime knowledge” (haiyang zhishi 海洋知识) on Chinese campuses, and one may advocate with China an Indian Ocean of harmony and exchange. Ptak implicitly favours such a vision (one must bear in mind that his booklet is based on a public lecture) and would like the Chinese to acknowledge the model of Fernand Braudel.

In spite of its small size the booklet offers many interesting considerations on the history of the Indian Ocean based on decades of research by the author. A table of contents would have been useful, but the reading can be done in an evening. However, it is written in German.