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.