Today, there are an estimated 115,200 speakers of the Mahri language, a distinct tongue spoken by the Mahra, an ethnic group that lives in modern-day Yemen, the Yemeni island of Socotra, Oman, Kuwait, and Northeastern Somalia. Mahri speakers have preserved their language orally, making it "one of the few, living remnants of the pre-Arabic language substrate that once stretched across the southern...