Arab-writing, not necessarily always Muslim. For example, the first person to describe Prague was Ibrahim ibn Yaqub, an Arabic-writing Jewish merchant from Cord

Arab-writing, not necessarily always Muslim. For example, the first person to describe Prague was Ibrahim ibn Yaqub, an Arabic-writing Jewish merchant from Cordoba. Arabic was a lingua franca of a territory that was significantly more religiously diverse than today. Both contemporary Iraq and Egypt were only about 50 per cent Muslim by the age of the Crusades. This applied in many other regions that are now 90+% Muslim and where we can hardly imagine any non-Islamic community today.