‘The world we thought we had lost turns out to have never existed in the first place’ (p. 241); a powerful reflection on L. Moch's (2003) statement about early modern migration, which T. stretches into the deeper past of the first two centuries of the Roman Empire. It encompasses the starting premise for this book. Using multiple approaches inherent in migration studies of the early modern period, it shows how ancient migration can be a subject of study in its own right. This is conducted with full awareness that migration, conceptualised through monitoring, control, census, passports, borders and the regulation of migrants as unwanted groups, is a modern invention, which has only indirect relevance to ancient Rome (p. 75). The volume has clear boundaries: to expose the nature of the Roman migration regime focusing on the city of Rome during the Principate (31 bc–ad 235), a highly urbanised environment that makes for a good case study (p. 6). Migration is defined as ‘the movement of persons who change their residence from one place to another on a permanent or semi-permanent basis. For the purposes of this book, migration constitutes movement by humans into and out of the city of Rome, in which the change of residence is of some duration’ (pp. 30–1). This statement is immediately followed by a caution that permanency is relative and the definition needs to be flexible.

The reader soon gets accustomed to such qualifying statements which chart the scrutiny of the disparate and fragmentary evidence. These sit alongside the highly quantitative examination of the data-sets and statistical guestimates used to test hypotheses about migration patterns. The experiments are carried out with the recognition that they are being applied to a society that has left few of the necessary figures, and which had little interest in acquiring them. Herein lies the paradox, implicitly acknowledged and revealed within the work: the study of a coherent phenomenon – migration – that was not recognised as such within the context being studied. This may appear to be a futile endeavour but, with T.’s careful scrutiny of multiple strands of inquiry simultaneously, it challenges underlying assumptions about ancient human mobility, the position of outsiders and hence the nature of the (urban) community in this period. His findings are strengthened by the fact that other studies, using different approaches and contexts, are reaching similar conclusions about the movement of people in the ancient Mediterranean (e.g. C. Broodbank, The Making of the Middle Sea [2013]; S. Hin, The Demography of Roman Italy [2013]; P. Horden and N. Purcell, The Corrupting Sea [2000]; E. Isayev, Migration, Mobility and Place in Ancient Italy [2017]; M. Lavan, Slaves to Rome: Paradigms of Empire in Roman Culture [2013]).

In modelling prominent forms of migration into the city of Rome, T. engages with the systems approach employed by early modern scholars, which considers how various types of migration related to each other and their social context (pp. 26–7). In his analysis methodologies are critically assessed: he cautions about the use of epigraphy to create statistics, which he argues is only meaningful within a sample (pp. 19–20); seemingly coherent categories are destabilised – there is no sharp distinction between forced and voluntary mobility, which are points on a spectrum of dependency and independency; some people who seem to move freely are shown to be enmeshed in a web of socio-economic obligations, or forced to move due to their living conditions (pp. 32–4); the distinction between slave and free, beyond the legal context, is undermined as freedmen continued to have ties and commitments to their previous masters. It is, therefore, with great caution that in Chapter 2 T. provides a series of guestimates applied to ten types of movement that highlight its variety (pp. 63–71). In combination with more concrete data he demonstrates that the total immigrant population was 20–30%. Its origin was primarily from within the Empire, and a significant proportion from Italy, hence most coming into the city were Roman subjects and slaves. Of this movement, 10% was state driven, 40% voluntary and 50% forced (pp. 72–4). Its variety means there can be no one single explanatory model nor ‘causative mechanism’.

The third chapter takes on issues that resonate with twenty-first-century migration debates: control, access, deportation (expulsion) and citizenship. The Roman state, however, had no migration policy. There was no specific status reserved for immigrants (half of whom would have been citizens anyway, p. 80), origin was not key to identity, and the legal position which separated peregrini and citizens declined over time. As citizenship was not territorially defined, the concern for regulations was status not origin, and expulsions were not so much immigration controls as symbolic acts (pp. 94–104). None of this implies that the Roman migration regime was lenient, as that would suggest movement was thought of as a problem. It is possible, however, to push this even further than allowed for in the volume and to question whether to consider the evidence in terms of a ‘migration regime’ is to assume a framework and coherence to a process that was not articulated as such in this ancient context.

Chapters 4 and 5 take on the demographics and gender balance of mobility, and ‘urban graveyard’ and ‘depressed fertility’ theories: the former purports that due to high mortality rates urban centres could not reproduce themselves, the latter, that immigrant populations had lower rates of marriage, and hence fertility, than local populations. Although both theories resonate with the ancient evidence, T. is cautious when needed; for example, as regards the assumption that movement was largely rural–urban, when in fact it was more cyclical, including more than a single trajectory. Still, there is likely to have been high mortality and lower fertility in Rome, and an outside supply of people was needed to keep the population stable. The population ‘deficit’ is calculated at some 27%, which is comparable to figures, derived from other data, for the proportion of communities composed of outsiders (pp. 167–8). Some three quarters of this external ‘supply’ was male – mainly young adults who moved individually. Females seem to have moved primarily in the context of marriage (pp. 118, 140). The issue is whether women would have been noticeable if they did not move in such a context; the increasing bioarchaeological data will have much to contribute here.

In Chapter 6, the relation between migration and Rome's labour market is analysed, incorporating push–pull factors. Among the complexities addressed are the high rate of slave labour and the low visibility of migrants in ancient sources interested in the labour market. Still, there is enough evidence to show that, in the openness of the city's labour market structure, there was no role for a dichotomy between migrant and non-migrant labour, nor for ethnicity – whether for slave or hired labour. It was not so much labour itself that attracted migrants to the city, but the potential of improving one's situation (p. 175).

In Chapter 7 T. turns to acculturation. His additional insight builds on increasing challenges to the problematic assumption that immigrants cluster together in their new place of residence, naturally forming diasporic enclaves (see e.g. E.S. Gruen, Diaspora. Jews amidst Greeks and Romans [2002]; E. Isayev, ‘Emerging Diasporas? Oscan-speaking Mamertines, Romans and Italia’, in H. Meller et al. [edd.], Migration and Integration from Prehistory to the Middle Ages [in press]; N. Luraghi, The Ancient Messenians. Constructions of Ethnicity and Memory [2008]). The multicultural community in Rome may be better analysed in terms of networks with fluid (weak) ties rather than group formation. There is no evidence for a migrant cemetery in the city, even Jewish catacombs were few in the early Empire. Beyond family clustering we struggle to find ethnic graveyards and, as T. notes, Egyptian or Egyptianising objects in graves have little to do with Egyptian immigrants (p. 21). Origin was only one identity marker that might appear on a grave stele. What ethnic indications there are show the constructed nature of such identity (p. 214). The idea of foreignness in Rome may have been a strong one, but who was foreign changed over time (pp. 206–8). T. concludes that, as a rule, migrants did not cluster together, nor did they preserve their own language or use economic or religious associations to foster loyalty or socio-cultural traditions (p. 238).

The propositions put forward by T. are crucial for the rapidly increasing research on migration, which will test and refine them, especially as new sources of evidence emerge (e.g. from bioarchaeology). In exposing the constructed nature of the categories and structures through which ancient (and modern) migration is studied, this volume provides the stimulus for examining the themes associated with human mobility from the perspective of the ancient world. We now need to ask what would such narratives look like if they were to be considered within the frameworks and terms available in the past.