Why did Arabic replace the Egyptian language in everyday speech?

The transition from the Coptic language—the final stage of the ancient Egyptian language—to Arabic in everyday speech was a slow, gradual process that unfolded over several centuries following the Islamic conquest in the 7th century.12

Several factors contributed to this linguistic shift:

• Administrative and Scholarly Influence: Arabic became the language of the bureaucracy by the early 8th century. The desire of the local population to engage with the ruling and learned elite provided a strong incentive to adopt the language of administration and scholarship.3
• Social Integration: The immigration of Arab tribesmen and their subsequent intermarriage with the indigenous population facilitated the spread of the language.3
• Urban Centers: Garrison towns like Al-Fustat served as primary centers of Arabization, as they were the only areas with an Arab majority, necessitating that native inhabitants acquire knowledge of Arabic.2
• Widespread Adoption: By the 12th century, Arabic had become the common language even among Christian Copts, with Coptic relegated primarily to liturgical use within the Coptic Orthodox Church.1