Does the confinement of prophethood and scripture to Abraham and his descendants mean that revelation was restricted to the Middle East and the Arabian Peninsula, or that Abraham's descendants intermarried with other peoples in various parts of the world?

The sacred texts do not confirm or deny the exclusivity of prophethood to the Middle East after Abraham (peace be upon him). The Qur'an's mention of prophets from this region does not mean that messengers were not sent to other nations, for Allah has not narrated to us the accounts of all His messengers. The Qur'an limited its mention to the prophets of these nations primarily to address the Arabs and because they had knowledge of these peoples, which made the lessons drawn from them more impactful. The Prophetic Sunnah states the number of prophets to be 124,000 and messengers to be 315. The legal proof was established for all creation by the covenant Allah took from the children of Adam when they emerged from their fathers, and by innate human disposition (fitra). We do not know a specific reason for this region being the cradle of prophethoods. The claim that prophethood was confined to the Middle East is a baseless misconception promoted by atheists.