Abbasid – Carolingian alliance An Abbasid – Carolingian alliance was attempted and partially formed during the 8th to 9th century through a series of embassies , rapprochements and combined military operations between the Frankish Carolingian Empire and the Abbasid Caliphate or the pro - Abbasid Muslim rulers in Spain . These contacts followed the intense conflict between the Carolingians and the Umayyads , marked by the Battle of Tours in 732 , and were aimed at establishing a counter - alliance with the faraway Abbasid Empire . Slightly later , another Carolingian - Abbasid alliance was attempted in a conflict against the Byzantine Empire . Background . The Islamic invasion of Gaul from 719 to 759 was a period of intense conflict between the Carolingians and the Umayyads , marked by the Battle of Tours in 732 . Umayyad forces were finally expelled from Gaul with the recovery of Narbonne in 759 by Pepin the Short , but the Umayyad presence in Spain continued to represent a strong threat to the Carolingians . Contacts under Pepin the Short . Embassies . Contacts between the Carolingians and the Abbasids started soon after the establishment of the Abbasid Caliphate and the concommital fall of the Umayyad Caliphate in 751 . The Carolingian ruler Pepin the Short had a powerful enough position in Europe to " make his alliance valuable to the Abbasid caliph of Baghdad , al - Mansur " . Former supporters of the Umayyad Caliphate were established firmly in southern Spain under Abd ar - Rahman I , and constituted a strategic threat both to the Carolingian on their southern border , and to the Abbasid at the western end of their dominion . Embassies were exchanged both ways , with the apparent objective of cooperating against the Umayyads of Spain : a Frank embassy went to Baghdad in 765 which returned to Europe after three years with numerous presents , and an Abbasid embassy from Al - Mansur visited France in 768 . Commercial exchanges . Commercial exchanges occurred between the Carolingian and Abassid realms , and Arabic coins are known to have spread in Carolingian Europe in that period . Arab gold is reported to have circulated in Europe during the 9th century , apparently in payment of the export of slaves , timber , iron and weapons from Europe to Eastern lands . As a famous example , the 8th century English king Offa of Mercia is known to have minted copies of Abbasid dinars struck in 774 by Caliph Al - Mansur with " Offa Rex " centered on the reverse amid inscriptions in Pseudo - Kufic script . Charlemagne ' s alliance . Military alliance in Spain ( 777 - 778 ) . In 777 , pro - Abbasid rulers of northern Spain contacted the Carolingian to request help against the powerful Umayyad Caliphate in southern Spain , still led by Abd ar - Rahman I . The " Spanish Abbasids sought support for their cause in Pepin ' s Francia ; he was content to oblige because the Cordoban dynasty posed a constant military threat to southwestern France " . Sulayman al - Arabi the pro - Abbasid Wali ( governor ) of Barcelona and Girona sent a delegation to Charlemagne in Paderborn , offering his submission , together with the allegiance of Husayn of Zaragoza and Abu Taur of Huesca in return for military aid . The three pro - Abbasid rulers also conveyed that the caliph of Baghdad , Muhammad al - Mahdi , was preparing an invasion force against the Umayyad ruler Abd al - Rhaman I . Following the sealing of this alliance at Paderborn , Charlemagne marched across the Pyrenees in 778 " at the head of all the forces he could muster " . His troops were welcomed in Barcelona and Girona by Sulayman al - Arabi . As he moved towards Zaragoza , the troops of Charlemagne were joined by troops led by Sulayman . Husayn of Zaragoza , however , refused to surrender the city , claiming that he had never promised Charlemagne his allegiance . Meanwhile , the force sent by the Baghdad caliphate seems to have been stopped near Barcelona . After a month of siege at Zaragoza , Charlemagne decided to return to his kingdom . On his retreat , Charlemagne suffered an attack from the Basques in central Navarra . As a reprisal he attacked Pamplona , destroying it . However on his retreat north his baggage train was ambushed by the Basques at the Battle of Roncevaux Pass August 15 , 778 . Carolingian presence remained south of the Pyrenees however , and the city of Girona was captured in 785 , and they then concentrated on expanding their rule to Vic h , Caserras and Cardona . The Muslims made their last incursion in Gaul in 793 , where they sacked the suburbs of Narbonne , and defeated William of Gellone , count of Toulouse near Carcassonne . Later contacts . After these campaigns , there were again numerous embassies between Charlemagne and the Abbasid caliph Harun al - Rashid from 797 , apparently in view of a Carolingian - Abbasid alliance against Byzantium , or with a view to gaining an alliance against the Umayyads of Spain . Strategic interest . Indeed , " Charles ' s conflict with the Umayyad Emir of Cordova made him an ally of the Abbasid emir of Baghdad , the celebrated Harun al - Rashid " , and they were " forming a pact against a common enemy - namely the Muslim rulers in Umayyad Spain " . For Charlemagne , the alliance may also have functioned as a counterweight against the Byzantine Empire , which was opposed to his role in Italy and his claim to the title of Roman Emperor . For Harun al - Rashid , there was an advantage in having a partner against his rivals in Umayyad Spain . Embassies . Three embassies were sent by Charlemagne to Harun al - Rashid ' s court and the latter sent at least two embassies to the Charlemagne . Harun al - Rashid is reported to have sent numerous presents to Charlemagne , such as aromatics , fabrics , a clock , a chessboard , and an elephant named Abu ' Abbas . The automatic clock was a water - clock made of brass , described in the 807 " Royal Frankish Annals " . It marked the 12 hours with balls of brass falling on a plate every hour , and also had twelve horsemen who appeared in turn at each hour . The 797 embassy , the first one from Charlemagne , was composed of three men , the Jew Isaac ( Isaac Judaeus , probably as interpreter ) , Lantfrid and Sigimud , and Harun al - Rashid was described as " Aaron , king of the Persians " . Four years later in 801 , an Abassid embassy arrived in Pisa , composed of " a Persian from the East " and one envoy " Emir Abraham , probably Harun al - Rashid ' s governor in North Africa , Ibrahim ibn al - Aghlab , with news about Jew Isaac that he was returning with numerous presents . They met with Charlemagne who was present in Italy at that time . In 799 , Charlemagne sent another mission to the Patriarch of Jerusalem . Apparently led by encouragements from Spain , Louis the Pious , king of Aquitaine , captured Barcelona in 801 , but failed to extend his conquests to Tortosa , which would remain Muslim for the next 300 years . In 802 , a second embassy was sent by Charlemagne , which returned in 806 . In 807 , Rodbertus , Charlemagne ' s ambassador died as he returned from Persia . Harun al - Rashid is also reported to have offered the custody of the Holy places in Jerusalem to Charlemagne . In 807 , Abdallah , " sent by the king of the Persian " , reached Charlemagne in Aachen accompanied by two monks from Jerusalem , George ( a German named Egilbaldus , prior of the Monastery of the Mount of Olives ) and Felix , envoys of the Patriarch Thomas . They also brought many gifts , including a clock ( " Horologium " ) . The third and final embassy was sent by Charlemagne in 809 , but it arrived after Harun al - Rashid had died . The embassy returned in 813 with messages of friendship , but little concrete results . Artistic influences . Various Islamic influences seem to appear in Christian religious architecture such as the multi - colored tile designs which may have been inspired by Islamic polychromy in the 800 CE gatehouse at Lorsch Abbey . Early Carolingian architecture generally combines Roman , Early Christian , Byzantine , Islamic and Northern European designs . In the Byzantine Empire from 723 to 842 , Islam and Judaism influenced a Christian movement towards the destruction of images this time , an event known as " Iconoclasm " . According to Arnold Toynbee , it is the prestige of Islamic military successes in the 7 - 8th centuries that motivated Byzantine Christians into evaluating and adopting the Islamic precept of the destruction of idolatric images . Charlemagne himself attempted to follow the iconoclastic precepts of the East Roman Emperor Leo Syrus , but this was stopped by Pope Hadrian I . Aftermath . It seems that in 831 , Harun al - Rashid ' s son al Ma ' mun also sent an embassy to Louis 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 . See also . Foreign alliances of France