A few years ago, Ahmad Al-Jallad, a professor of Arabic and Semitic linguistics at Leiden University, in the Netherlands, opened his e-mail and was excited to see that he had received several photographs of rocks. The images—sent by Al-Jallad’s mentor, Michael Macdonald, a scholar at Oxford who studies ancient inscriptions—were of artifacts from a recent archeological survey in Jordan. Macdonald pointed Al-Jallad’s attention to one in particular: a small rock covered with runelike marks in a style of writing called boustrophedon, named for lines that wrap back and forth, “like an ox turning in a field.” It was Safaitic, an alphabet that flourished in northern Arabia two millennia ago, and Al-Jallad and Macdonald are among a very small number of people who can read it. Al-Jallad began to transcribe the text, and, within a few minutes, he could see that the rock was an essential piece of a historical puzzle that he had been working on for years.

The history of Arabia just before the birth of Islam is a profound mystery, with few written sources describing the milieu in which Muhammad lived. Historians had long believed that the Bedouin nomads who lived in the area composed exquisite poetry to record the feats of their tribes but had no system for writing it down. In recent years, though, scholars have made profound advances in explaining how ancient speakers of early Arabic used the letters of other alphabets to transcribe their speech. These alphabets included Greek and Aramaic, and also Safaitic; Macdonald’s rock was one of more than fifty thousand such texts found in the deserts of the southern Levant. Safaitic glyphs look nothing like the cursive, legato flow of Arabic script. But when read aloud they are recognizable as a form of Arabic—archaic but largely intelligible to the modern speaker.

The inscription on Macdonald’s rock included the name of a person (“Ghayyar’el son of Ghawth”), a narrative, and a prayer. It was the narrative that stood out to Al-Jallad. Reading it aloud, he noted a sequence of words repeated three times, which he suspected was a refrain in a poetic text. This would make it the oldest known record of literary expression in Arabic—evidence, however slim, of a written poetic tradition that had never been explored.

Al-Jallad, who is thirty-two, was born in Salt Lake City. His father came to the United States from Jordan to attend college, and met his mother, who is from Texas, at Weber State University, in Utah. The family moved to Kuwait in 1989 but returned a year later, at the outset of the first Gulf War, and settled near Tampa. “We didn’t speak Arabic at home, because my mother didn’t understand it,” Al-Jallad told me. “The only connection I had to the Middle East was through books about ancient civilizations.” When Al-Jallad was a teen-ager, one of his favorite books was “Noah’s Flood,” a study arguing that the flood narratives of the Bible, the Epic of Gilgamesh, and other ancient texts were inspired by the flooding of the Black Sea, around 5600 B.C. “The mix of archeology, geology, and ancient languages blew my mind,” Al-Jallad said. “I had no idea if it was right, but I was hooked.”

As an undergraduate, at the University of South Florida, Al-Jallad got a job at a library on campus and read whatever he could find on Near Eastern civilizations. “I tried to learn Akkadian, so I could read the original Epic of Gilgamesh, but didn’t get very far,” he said. He wrote to professors in Semitic studies around the country asking for guidance. They all replied, “Nobody starts with Akkadian—you need to learn Biblical Hebrew, classical Arabic, and Syriac first,” he said. For two years, he studied those languages on his own in the library. After graduating, he was accepted into Harvard’s doctoral program in Semitic philology.

Al-Jallad is now one of the world’s foremost authorities on early Arabic, leading excavations around the Middle East. The study of early Islam has traditionally depended not on rock inscriptions but on chronicles and literary sources composed a few centuries after Muhammad’s death—a method of research that Al-Jallad likens to reading the history of North America entirely from the perspective of the first European settlers. He is confident that scholars will soon be able to tell the earliest history of Islam using evidence from the time of Muhammad’s birth. “We will find texts from the lifetime of the Prophet Muhammad,” he said. “I am one-hundred-per-cent certain of that. It’s just a matter of time.”

The effort to decode the Safaitic texts began in the spring of 1857, when a young Scotsman named Cyril Graham set off from Jerusalem on a tour of Syria. Like many other European visitors to the Holy Land, Graham was interested in the sites of Biblical archeology, which, he wrote in 1858, would offer proof of “the invariable accuracy of the sacred Historian.” While travelling through the desert, he learned from Bedouin guides about a volcanic tableland called the Harrah, which was littered with strange rock inscriptions. The guides led him to the outskirts of Safa, a volcanic region southeast of Damascus. At night, while his guides were asleep, Graham left the camp and, in bright moonlight, discovered a plain covered with inscribed rocks:

I gazed on these marvelous stones, and tried to picture to myself what people they were who centuries ago had lived here and had employed themselves in carving these curious symbols. What did it all mean?

Graham announced his discovery at the Royal Geographical Society, and other expeditions followed. In 1877, an Orientalist from Ottoman Edirne deciphered most of the alphabet, bringing the language of the inscriptions into blurry focus. But, even as the script became legible, its references remained cryptic. “The first scholars who worked on the inscriptions did so in an impressionistic sort of way,” Al-Jallad said. “They’d rely almost exclusively on classical-Arabic dictionaries to decipher the texts, or, worse, they’d ask the local Bedouin what they meant.” Enno Littmann, an Orientalist who visited Syria in 1899, with a contingent from Princeton University, and completed the decipherment, labored over what he found on the rocks. Alongside scores of theophoric names (“God the King,” “God Rewards”) were more puzzling appellations, such as “Changer of Undergarments,” “Branded on the Testicle,” and “He Rose and Shook.” Could these be old tribal nicknames? Or had the words been deciphered incorrectly?

For a century, Safaitic remained an almost hidden corner of Arabian epigraphy, an already esoteric area. But, by 2007, when Al-Jallad arrived at Harvard, the field was undergoing a transformation. Digital photography was making a wealth of new inscriptional data available to scholars, and the number of Safaitic texts discovered in the Levant had swollen dramatically, vastly exceeding the number of Latin inscriptions recorded at Pompeii, the Roman Empire’s most famous source of graffiti. (A few Safaitic inscriptions were even found in Pompeii, on the walls outside a small theatre, probably scribbled by Arabian members of the Roman army.) Michael Macdonald amassed a vast collection of photographs of these texts and launched a digital Safaitic database, with the help of Laïla Nehmé, a French archeologist and one of the world’s leading experts on early Arabic inscriptions. “When we started working, Michael’s corpus was all on index cards,” Nehmé recalled. “With the database, you could search for sequences of words across the whole collection, and you could study them statistically. It worked beautifully.”