LAN BATOR, Mongolia - China built the Great Wall more than 2,000 years ago to keep out invaders from the north. But the Chinese are having a harder time repulsing modern interlopers like these: long-haired Mongolian men in black, whose office décor features a wolf pelt, a portrait of Genghis Khan and a music store poster of Eminem.

So the Chinese police got nervous when they heard that Hurd was crossing the Gobi Desert, coming down from Mongolia, 600 miles to the north. With their new hit CD, "I Was Born in Mongolia," Hurd, a heavy metal, Mongolian-pride group, was coming for a three-day tour, culminating Nov. 1 with a performance in Hohhot, capital of the Inner Mongolia Autonomous Region.

"The morning we were to get on the train, the translator guy called and said 'Your performances are cancelled,' " Damba Ganbayar, Hurd's keyboardist and producer, said glumly as he lounged in a white plastic chair. "He said, 'I will call with details.' I never got the details."

The details, according to reports from Hohhot, were that riot policemen and trucks surrounded the college campus where the group was to play. They checked identity cards, detained four people overnight and dispersed about 2,000 frustrated concertgoers into the autumn night.

In the next several days, the Chinese authorities shut down three Mongolian-language chat forums, according to the Southern Mongolia Human Rights Information Center, a New York-based group that tracks "Chinese colonialism" in what some call the southern end of Greater Mongolia.

"Banned in Hohhot" may not have an epic ring to it, but it is a sign of the times.

With reports of local protests almost daily fare in China, the authorities are increasingly nervous also about ethnic minorities. In late October, several days of fighting erupted between Hui Muslims and Han Chinese - China's dominant ethnic group - in central Henan Province after a traffic accident.

During the 1960's, the Chinese-Soviet split kept Mongolia, a Soviet satellite nation, apart from China's Inner Mongolia. Today, the Chinese region is home to four million ethnic Mongolians, almost double the 2.5 million in the country of Mongolia. But Chinese migration to Inner Mongolia over the years has left the ethnic Mongolians there vastly outnumbered by 18 million Han Chinese.

In recent years, barriers have gone down between those two Mongolias as China has become its northern neighbor's largest trading partner and foreign investor. With Inner Mongolia's economy growing by 22 percent during the first nine months of this year, officials in the two Mongolias agreed in October to open a free-trade zone where the Trans-Mongolian Railway crosses into China.

On the cultural front, music groups from here often appear on Inner Mongolia's Mongolian-language channel. Hurd, which means speed, has done three concert tours in Inner Mongolia since 2000. It claims to be the most popular rock group for Mongolians on both sides of the border.

"In 2000, it was very Soviet-style, with lots of policemen around with flashlights, very disciplined concerts," Mr. Damba Ganbayar recalled. "Later, it became more relaxed, like normal rock concerts."

"Even so, they advised us not to say, 'We Mongolians are all together!' or 'All Mongolians rise up and shout!' " the keyboardist continued. "People would shout, 'Genghis!' But it was nothing political."

But on later visits south of the border, he noticed a growth in Mongol pride.

"More and more the young people say, 'We want to keep the Mongolian language and the traditions,' " he said. "I met a guy with a Mongolian name, and he shouted, 'I am Mongolian!' - in Chinese. I met many like that."

Encounters between Mongolians and Inner Mongolians are a bit like encounters between Mexicans and New Mexicans. Many Mongols here say they consider Inner Mongolians to be more Chinese than Mongolian. When people here travel south, they do not say they are going to Inner Mongolia, but to China.

"We don't have an Inner Mongolian problem," a Chinese diplomat in the region said in an interview. "Most of the Inner Mongolian population has been 'Han-ized.' They speak Chinese, think like Chinese. Hohhot is like any other Chinese city."

Munh-Orgil Tsend, Mongolia's foreign minister, said in an interview, "For us, Inner Mongolia is a province of China that happens to have ethnic brother on other side of the border."

On the northern side of the border, Hurd's nationalist identity has grown over the last two years, a time when the group did not record any new songs.

"Hurd's national pride and love of homeland takes the ethos of Bruce Springsteen's 'Born in the U.S.A.' to a new level," said Layton Croft, an American foundation representative and musician here, who attended one of their concerts in October. "There is a loyal, mostly rural, Mongolian fan base for such music."

Hurd's Mongol nationalism is aimed at that audience: young Mongolians who now leave the country for work, the men in construction in South Korea, the women as 'hostesses' in Macao.

But the "I Was Born in Mongolia" CD, with its paeans to a "land of great legendary heroes," came out here as ethnic Mongolians in China were discovering that a Han Chinese-owned company was taking over administration of the Genghis Khan Mausoleum, the region's biggest tourist money-maker. Entrusted to the care of the Darhad Mongolian tribe since 1696, this shrine holds relics of the great conqueror, including his saddle and his black bow.

The actual burial place of Genghis Khan, who died in 1227, is not known, and has been the object of several archeological expeditions. But construction of a new "mausoleum" by Dong Lian, the Chinese company, prompted protests by Mongolians who see the move as another power grab by Chinese settlers.

From the Chinese side, "anything associated with nationalism, separatism, political rights, they want to suppress it," said an Inner Mongolian trader here who asked not to be identified.

In the best-known case, a bookstore owner who goes by one name, Hada, is serving a 15-year sentence after being convicted of separatism in 1996.

But with the canceling of concerts by Hurd and Horda, an Inner Mongolian band, some fear new restraints on Mongolian cultural expression.

"The government is shutting down a lot of music shops, confiscating a lot of music tapes," said Enhebatu Togochog, who runs the Southern Mongolian information center in New York. "They say they are purifying the cultural market."