Fustat has become the largest Jewish community in the East by the mid-ninth century.

Hebrew is considered the primary language of trade between the Carolingian and 'Abbasid domains because Jews often serve as a mercantile bridge between the Latin- and Arab-speaking worlds,

Sallam, a Spanish Jewish merchant said to speak thirty languages, had in 845 reportedly reached China.

Ibn Laid al-Hassan, a Muslim traveler, writes of riots in 850, in China's Kansu province in which Jews are counted among the dead.