the Pious. These embassies also seem to have had the objective of promoting commerce between the two realms. After 814 and the accession of Louis the Pious to the throne, internal dissensions prevented the Carolingians from further ventures into Spain. Almost a century later Bertha, daughter of Lothar II and mother of several tenth-century Italian kings, is reported to have sent an embassy to the Abbasid caliph Al-Muktafi, requesting friendship and a marital alliance. Notes References Margaret Deanesly A History of Early Medieval Europe Taylor & Francis, London Methuen & Co, Ltd David Levering Lewis God's Crucible Islam and the Making of Europe, 570-1215 W.W. Norton, 2008 Gene W. Heck When worlds collide: exploring the ideological and political foundations of the clash of civilizations Rowman & Littlefield, 2007 Jack Goody Islam in Europe, Polity Press, 2004, Joseph F. O'Callaghan A History of Medieval Spain Cornell University Press, 1983 Constantine VII Prophyrogentius, Emperor of the East. De Administrando Imperio, pp. 905–959. Dumbarton Oaks Center for Byzantine Studies, 2008. . Scholz, Bernhard Walther (1931- ). Rogers, Barbara (1945- ). Nithardus (ca 790-ca 845). Histories (ang.) (2000). Carolingian chronicles : Royal Frankish annals and Nithard's Histories. University of Michigan Press. . OCLC 867938000 Kennedy, H. (1986). The early Abbasid Caliphate a political history. London: Croom Helm. OCLC 0709900929 Muratori, Lodovico Antonio (1762). Dell'anno 601 dell'era volgare fino all'anno 840, pp. 465. Olzati. OCLC 258143787. Foreign relations of the Abbasid Caliphate 8th-century military alliances 9th-century military alliances Charlemagne Harun al-Rashid Military alliances involving France Military history of Al-Andalus Military history of the Abbasid Caliphate 8th century in Al-Andalus 9th century in Al-Andalus 8th century in Francia Military history of the Carolingian Empire 8th century in the Abbasid Caliphate 9th century in the Abbasid Caliphate Foreign relations of the Carolingian Empire