Al-Azhar University in Cairo, Egypt was founded around 970-972 CE, making it the oldest continuously operating university in the world. It focuses on Islamic culture and religious teachings. The use of paper, invented in China, spread widely through the Islamic empire, enabling the easier creation and sale of books. Business was conducted using checks, a precursor to modern credit. As the Abbasid empire expanded, more people learned Arabic, the official language, blending information from diverse cultures under Islamic rule. Scholars from various backgrounds across the empire were drawn to learning in this time, including non-Muslims.