MOSCOW – A Russian archaeologist says he has found the lost capital of the Khazars, a powerful nation that adopted Judaism as its official religion more than 1,000 years ago, only to disappear leaving little trace of its culture.

Dmitry Vasilyev, a professor at Astrakhan State University, said his nine-year excavation near the Caspian Sea has finally unearthed the foundations of a triangular fortress of flamed brick, along with modest yurt-shaped dwellings, and he believes these are part of what was once Itil, the Khazar capital.

By law Khazars could use flamed bricks only in the capital, Vasilyev said. The general location of the city on the Silk Road was confirmed in medieval chronicles by Arab, Jewish and European authors.

“The discovery of the capital of Eastern Europe’s first feudal state is of great significance,” he told The Associated Press. “We should view it as part of Russian history.”

Kevin Brook, the American author of “The Jews of Khazaria,” e-mailed Wednesday that he has followed the Itil dig over the years, and even though it has yielded no Jewish artifacts, “Now I’m as confident as the archaeological team is that they’ve truly found the long-lost city,

The Khazars were a Turkic tribe that roamed the steppes from Northern China to the Black Sea. Between the 7th and 10th centuries they conquered huge swaths of what is now southern Russia and Ukraine, the Caucasus Mountains and Central Asia as far as the Aral Sea.

Itil, about 800 miles south of Moscow, had a population of up to 60,000 and occupied 0.8 square miles of marshy plains southwest of the Russian Caspian Sea port of Astrakhan, Vasilyev said.

It lay at a major junction of the Silk Road, the trade route between Europe and China, which “helped Khazars amass giant profits,” he said.

The Khazar empire was once a regional superpower, and Vasilyev said his team has found “luxurious collections” of well-preserved ceramics that help identify cultural ties of the Khazar state with Europe, the Byzantine Empire and even Northern Africa. They also found armor, wooden kitchenware, glass lamps and cups, jewelry and vessels for transporting precious balms dating back to the eighth and ninth centuries, he said.

But a scholar in Israel, while calling the excavations interesting, said the challenge was to find Khazar inscriptions.

“If they found a few buildings, or remains of buildings, that’s interesting but does not make a big difference,” said Dr. Simon Kraiz, an expert on Eastern European Jewry at Haifa University. “If they found Khazar writings, that would be very important.”

Vasilyev says no Jewish artifacts have been found at the site, and in general, most of what is known about the Khazars comes from chroniclers from other, sometimes competing cultures and empires.

“We know a lot about them, and yet we know almost nothing: Jews wrote about them, and so did Russians, Georgians, and Armenians, to name a few,” said Kraiz. “But from the Khazars themselves we have nearly nothing.”

The Khazars’ ruling dynasty and nobility converted to Judaism sometime in the 8th or 9th centuries. Vasilyev said the limited number of Jewish religious artifacts such as mezuzas and Stars of David found at other Khazar sites prove that ordinary Khazars preferred traditional beliefs such as shamanism, or newly introduced religions including Islam.

Yevgeny Satanovsky, director of the Middle Eastern Institute in Moscow, said he believes the Khazar elite chose Judaism out of political expediency — to remain independent of neighboring Muslim and Christian states. “They embraced Judaism because they wanted to remain neutral, like Switzerland these days,” he said.

In particular, he said, the Khazars opposed the Arab advance into the Caucasus Mountains and were instrumental in containing a Muslim push toward eastern Europe. He compared their role in eastern Europe to that of the French knights who defeated Arab forces at the Battle of Tours in France in 732.

The Khazars succeeded in holding off the Arabs, but a young, expanding Russian state vanquished the Khazar empire in the late 10th century. Medieval Russian epic poems mention Russian warriors fighting the “Jewish Giant.”

“In many ways, Russia is a successor of the Khazar state,” Vasilyev said.