To write “Trickster Travels,” (Farrar, Straus & Giroux, 436 pages, $30), her imaginative and erudite new study of a famous border-crosser, Natalie Zemon Davis crossed a few boundaries of her own. Ever since her 1983 book “The Return of Martin Guerre,” which focused on a bizarre case of stolen identity in 16th-century France, Ms. Davis has pioneered techniques that have become standard practice for today’s best historians. Her ability to coax insights from seemingly dry archives, her use of the strategies of anthropology and literary criticism, and her pursuit of large historical insights through small-scale stories of private lives all make Ms. Davis one of the most influential historians alive.

All of those characteristic strengths return in “Trickster Travels.” But this time Ms. Davis has changed her quarry: Instead of her usual subjects, early modern France and the lives of women, she is now on the trail of a North African Muslim man. And tracking down the true story of Leo Africanus, the author of a famous 16th-century book about the geography and culture of Africa, is no easy job.

For one thing, Leo Africanus was not his real name; it was given to him in his mid-30s, after he was kidnapped by Christian pirates in the Mediterranean and held prisoner in Rome. He received the names Joannes Leo at his Christian baptism in 1520, in honor of the man who sprinkled the holy water on him in St. Peter’s Cathedral, Pope Leo X. Before then, he had been al-Hasan al-Wazzan,a diplomat in the service of the sultan of Fez. And even after his conversion, he preferred to use the Arabic version of his Latin baptismal names, Yuhanna al-Asad.

Al-Wazzan, Joannes Leo, Yuhanna – his multiple names suggest the conflicting identities lived by this adventurous and adaptable man. Even before he wound up in a papal prison, al-Wazzan – as Ms. Davis calls him in the first part of her book – was an experienced negotiator across cultural boundaries. Born in Granada in the last years of Moorish rule, he left the city with his family at about age 6, when it fell to the Christian Spaniards in 1492. Like many other Muslim and Jewish refugees, he ended up in the North African city of Fez, a thriving metropolis of 100,000 souls. There al-Wazzan received the thorough education of a faqih, a scholar of Islamic law, which helped to equip him for a diplomatic career.As early as age 16,he took part in an embassy to the Songhay empire, an arduous journey that involved crossing the Atlas mountains and the Sahara desert.

Al-Wazzan’s knowledge of the Islamic world would grow steadily over the next decade and a half, as he traveled between Mali and Cairo, Mecca and Istanbul. The early 16th century was an extremely challenging time to be a Muslim diplomat, as Ms. Davis shows in her brief but lucid account of Islamic geopolitics. Like contemporary Christendom, the 16th-century Dar al-Islam, the land of Islam,was violently divided, despite its nominal religious unity.The sultan of Fez, al-Wazzan’s master, was under pressure from the Portuguese and Spanish, who were steadily expanding their influence on the Atlantic and Mediterranean coasts. He also had to fend off a religiously inspired challenge from his southern neighbor, Muhammad al-Qa’im, who claimed descent from the Prophet. At the same time, the Ottoman Turks were displacing the Egyptian Mamluks as the dominant power in the Middle East.Al-Wazzan was in Cairo during or shortly after the terrible Ottoman conquest of the city, which was accompanied by mass slaughter and looting.

It was on a trip between Cairo and Fez that al-Wazzan took the unintentional detour that would tear him away from his Islamic roots and write him into European history. Piracy was commonplace in the 16th-century Mediterranean: Christian and Muslim rulers alike financed pirates and benefited from the sale and ransom of captives. Indeed, the captain who took al-Wazzan’s ship in 1518, most likely off the Tunisian coast, was a Spanish nobleman,and the brother of a Catholic bishop. This connection helps to explain why al-Wazzan was handed over to Pope Leo X – perhaps, according to Ms. Davis, “as a ‘votive offering,’ as one observer called it, that won the pirate absolution for some of his excesses.”

This stroke of fate was the undoing of al-Hasan al-Wazzan and the making of Leo Africanus. We know very little about the motives behind his conversion to Christianity, but it seems safe to say that it was performed under duress: Only as a Christian could Leo, or Yuhanna al-Asad,as he called himself,earn release from prison. Once he got his freedom, however, Yuhanna found himself in one of the most educated and cosmopolitan circles of Renaissance Europe. Between 1520 and 1527, when he seems to have gone back to North Africa, he worked for several humanist cardinals, teaching the princes of the church about the Muslim world. He helped to correct a translation of the Koran,wrote a collection of lives of eminent Muslims, and started to assemble an Arabic dictionary, working closely with learned Jews like Elijah Levita, the author of an epic poem in Yiddish.

But Yuhanna al-Asad’s most important work was his “Cosmography and Geography of Africa.” Written in his newly learned, slightly awkward Italian, the “Geography” drew on Yuhanna’s years of travel and wide reading to explain a continent still largely mythical in the European imagination. The heart of “Trickster Travels” is Ms. Davis’s rich unfolding of this complicated text. Above all, she is interested in what she calls Yuhanna’s “double vision,” which “consciously moves back and forth between Europe and Africa, between the different cultures and politics of Africa, and between Islam and Christianity.” She argues convincingly, if sometimes a bit programmatically, that Yuhanna was a true cosmopolitan, disdaining racial and cultural stereotypes. With only a few perplexing exceptions, much analyzed by Ms. Davis, he steadily refused to insult the Islam in which he was raised, and to which he presumably returned at the end of his life.

“Presumably” is the best Ms. Davis can do with much, even most, of Leo Africanus’s story. “Trickster Travels” is not really the biography of a man – there is simply not enough known about Leo’s life,especially after he left Italy, to make a full biography possible. Rather, Ms. Davis is writing about texts: the texts Leo wrote, the texts he read and studied, and the cultural scripts he had to master in order to perform his many roles By introducing the modern reader to that world, in all its fascinating strangeness, Ms. Davis has written yet another eye-opening text of her own.

akirsch@nysun.com