Rock faces within the caves and dried riverbeds of Oman’s Dhofar governorate bear nearly 2400-year-old writings that snake across the surface in a mysterious script. For more than a century, these inscriptions—known as the Dhofari script—had defied decipherment. Now, in a study in press at the journal Jaarbericht Ex Oriente Lux, a linguist says he has deciphered the main subtype of the Dhofari script, and has found evidence that its alphabet didn’t originate in southern Arabia. The enduring enig...