Contents lists available at ScienceDirect Journal of Archaeological Science: Reports journal homepage: www.elsevier.com/locate/jasrep The spatiotemporal distribution of Late Viking Age Swedish runestones: A reflection of the Christianisation process and its speed Fredrik Charpentier Ljungqvist a,b,⁎ , Andrea Seim c a Department of History, Stockholm University, Stockholm, Sweden b Department of Geography, University of Cambridge, Cambridge, United Kingdom c Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, University of Freiburg, Freiburg, Germany ARTICLE INFO Keywords: Runestones Christianisation Viking Age Sweden Spatial analysis Geostatistical analysis Geographic Information System (GIS) ABSTRACT The Late Viking Age Swedish runestones are commonly acknowledged as early Christian monuments. Using geostatistical techniques and descriptive statistics, we systematically investigate the regional-to-local spatio- temporal patterns of 1302 ornamentally dated Swedish runestones regarding the timing and speed of the Christianisation process. After quantitative geostatistical analyses of the age distribution patterns of Swedish runestones, we evaluate whether the observed patterns correspond to the pace and pattern of Christianisation, as represented by the presence of mission bishoprics, early church sites, late pagan grave sites and royal estates. We identify seven distinct age groups of runestones and statistically significant regional-to-local spatiotemporal differences in the age and age spread of runestones. The oldest runestones, with the smallest age spread, are found in south-western medieval Sweden, and the youngest, as well as the largest age spread, in the north-east, respectively. We find that runestones are significantly older close to early ecclesiastical sites, regardless of the analytical level, and significantly younger near to late pagan graves. The results obtained are inconclusive as to whether runestones are older near royal estates. Our results support that the spatiotemporal patterns of ru- nestone sites mirror the timing of the Christianisation process and that geostatistical approaches to larger ar- chaeological or historical data sets can add new dimensions to the understanding of the spatial dimensions of past societal changes. 1. Introduction 1.1. Background Runestones are among the visually most prominent remnants from the Scandinavian Viking Age (c. 790–1100 CE) (Jesch, 1994, 2001; Sawyer, 2000; Imer, 2007; Klos, 2009; Bianchi, 2010; Zilmer, 2010; Stern, 2013). Often decorated with crosses and/or prayers, they are also indicative of the Christianisation process (Lager, 2002, 2003; Zilmer, 2011; Williams, 2016). The majority – over 2800 – of the known Viking Age runic stone inscriptions are within medieval Sweden's borders, and concentrated in the eastern province of Uppland. In comparison, only c. 250 runestones and fewer than 100 are known within the borders of medieval Denmark and Norway, respectively (Table 1; Fig. 1a). They are mainly a Late Viking Age phenomenon – from the late tenth century to the early twelfth century – though about 70 are dated prior to c. 950 CE. The runestones functioned as memorial stones for deceased re- latives (Jansson, 1987; Zachrisson, 1998; Sawyer, 2000) and likely served social or political purposes (Randsborg, 1980) and in particular may have attested statements or claims of inheritance rights (Sawyer, 1989, 2000), functioned as boundary markers (Larsson, 1990; Palm, 1992; Wilson, 1994; Johansen, 1997; Stille, 2014) and as a way to express Christianity (Lindqvist, 1915; Gardell, 1937; Palme, 1959; Segelberg, 1983; Gräslund, 1987; Herschend, 1994; Williams, 1999, 2016; Lager, 2002, 2003; Zilmer, 2011, 2012, 2013). The Late Viking Age runestones have generally been considered a form of Christian monument ever since the publication of Liljegren (1832). Subsequently, von Friesen (1913, 1933) attempted to divide the runestones into age classes, arguing, together with Ljungberg (1938), that their spatiotemporal distribution represented the geographical patterns of the gradual spread of Christianity across Scandinavia. Since then, the consensus has been that the runestone tradition originated in Denmark, spread northward to Norway and north-eastward through Sweden (Section 1.2). Segelberg (1983), Hultgård (1992), Williams (1996, 2016) and many others have emphasised the importance of the runestone material https://doi.org/10.1016/j.jasrep.2018.08.044 Received 10 May 2018; Accepted 17 August 2018 ⁎ Corresponding author at: Department of History, Stockholm University, SE-106 91 Stockholm, Sweden. E-mail address: fredrik.c.l@historia.su.se (F.C. Ljungqvist). Journal of Archaeological Science: Reports 21 (2018) 849–861 2352-409X/ © 2018 Elsevier Ltd. All rights reserved. T