Living on the fault line of Sino-Soviet relations requires a few adjustments for Qing Bola and his village of Mongolian herders located outside this border town.

When they ride horseback to the once-peaceful border a few miles away to cut winter grass for their livestock, they no longer speak to their old friends on the Soviet side.

In the village office, they stash away eight semiautomatic rifles and a bazooka just in case the formidable Soviet Army decides to cross the boundary line into China some day.

"The peaceful life has changed," said Qing, 51, the village manager. "We worry all the time about the livestock. One day they might be seized by the Russians."

But, he said after a pause, "The tension is not so serious. . . . "

For hearty villagers and townspeople who live within range of the Soviet rockets, life is much like that of an area prone to earthquakes or flooding. The constant, underlying tension keeps them vigilant and prepared for the worst, but it eventually gives way to the daily routine of life -- at least until the first sign of trouble.

In Manzhouli, a rough frontier town five miles from the border, no less than a third of its 30,000 people -- male and female -- serve in the civilian militia. But it takes a palpable threat of Soviet attack before guns are issued, military drills begin and the children and aged are moved to a neighboring area.

The main street of Manzhouli looks more like a prospecting town in America's Old West than a contemporary Chinese community sitting on the edge of the unthinkable.

There are young workers bundling up against the subzero weather, shopping in squat, wood-frame stores or eating a meal behind the frosted windows of a tavern. But there is no sign of uniformed men.

There are pony carts trotting down unpaved roads, their tall Mongolian drivers standing up to crack the reins. But there is no sign of armored vehicles.

Twenty-five miles west, just inside the border, is Qing Bola's village, a small cluster of mud and brick houses resting alone in the snowy Inner Mongolian plain, the only trace of human activity for dozens of miles.

Although this tiny, isolated community could well be the first casualty of a Soviet invasion, the threat of danger seemed to have little impact on their ritualistic life one December day when we unexpectedly dropped in.

It was slaughter day, and most of the 100 residents -- stocky people with square jaws and high-bridged noses emphasizing their Mongolian heritage -- took time away from their sheepherding chores to watch the carving of six prize cows.

Each household pushed a wheelbarrow across the village square to the steamy, bloody carcasses left on the flat surface of an old wood wagon and shoveled off a share -- 45 to 50 pounds to last for the rest of the winter.

Inside one of the houses, which was insulated by wood boards and old newspapers, an old woman was busily preparing a tray of freshly cut hooves to be made into special Mongolian stew. She shooed away several chickens and a plump pig from the cooking area to make room for her inquiring foreign guests.

In the village office, Qing and his wife readied an informal Mongolian greeting -- scalding milk tea, hard chewy cheese with a sour taste, porous grainy cheese with a sweet taste and a dollop of what appeared to be chicken fat to spread on the cheese and spoon into the tea.

Even though the customs of Qing's village once prevailed in the plain abutting the Mongolian border to the west, Mongolians today from a tiny minority in this frontier zone as result of a carefully designed policy of the Chinese Communist government.

With heavy concentrations of ethnic peoples on China's sensitive borders, leaders in Peking soon after taking power began encouraging migrations of the majority Han people to the strategically important frontiers. This way they could consolidate control over the ethnic minorities who tend to disregard national boundaries separating their clans.

For a town like Manzhouli, an old Mongolian stronghold that now boasts a Han population of 94 percent, the Chinese government had good historical reason to worry.

In the early 1900s, Manzhouli was turned into the last Chinese depot for a Russian-built railway that traversed all of Manchuria from the east and connected with the Trans-Siberian railway as it entered the Soviet Union.

As the last and most important link in the railway chain, Manzhouli was virtually run by Russian railway officials for years. In 1908 and 1929 the town was shelled and forcibly occupied by Russians after the Chinese government tried to reassert administrative control.

Today Manzhouli is firmly in Chinese hands, although the People's Liberation Army, apparently conceding to superior Soviet power across the border, has all but left its defense to the town's civilian militia. What this group lacks in weapons and training compared to the moderan Soviet Army, it makes up in high morale.

"If our town exists, we will fight to the end," said Mu Jun, 29, a carpenter who doubles as a militia squad leader. "If there is one person left, he will fight to the end."

Mu and five fellow militia officers who sat through an interview at the Manzhouli guest house originally thought they had a chance to prove their bravery in February 1979, when the Soviet Army staged a tremendous show of force at the border.

Apparently designed as a warning to the Chinese, who had invaded Vietnam, a Soviet ally, earlier that month, the Soviets sent reconnaissance planes into Chinese airspace, moved blank-firing tanks and howitzers right up to the border and illuminated Manzhouli with floodlights.

Expecting the worst, militia units handed out semiautomatic and automatic rifles, hand grenades and mines. Daily training sessions were held to practice firing antiaircraft guns, machine guns and flame throwers. Food was gathered and stored in air-raid tunnels. Some families were packed off to neighboring towns.

By early March the scare ended and life returned to normal. But the days of high anxiety further hardened the adults of Manzhouli and gave their children firsthand experience in Sino-Soviet politics.

"When I have a rifle in my hand and the situation is tense, the children know why," said Mu, who has a 5-year-old son. "All the kids knows the Russians are our enemy. The teachers tell them the Russians are evil."

As he finished his sentence, three fellow militia leaders chimed in like a chorus: "The Russians are the children's teachers."