At 93, Alfred Ngema's voice crackles thinly, but his memory is clear and his determination strong.

"This land is ours," he said. "It was given to my grandfather, Stuurman, by the Boers" -- the ancestors of the white Afrikaner minority who rule South Africa -- "a very long time ago, and no one has the power to take it away from us. If they try, then old as I am, I will refuse. Even if it is by them killing us, let us rather die here in the land of our forefathers."

A silence settled over the small group squatting around the old man in the shade of a peach tree beside his mud hut. The women of his family sat under another tree, a respectful distance away, listening intently and picking at their teeth with grass straws.

"You see," broke in his son, Moses Ngema, "we regard this place as something our forefathers built, our Carlton Centre" -- a reference to downtown Johannesburg's most imposing building complex.

"This is my father," he added, gesturing toward the old man, "and he will say that I must bring him here to bury him. He would never allow me to bury him in another place. He must be buried with his father."

Thus, in the intricate and sacred pattern of African ancestry, are the 4,000 people of the Kwangema community bound up with the 140,000 acres of land given to their ancestor 125 years ago in a beautiful grassland valley near the eastern Transvaal town of Piet Retief.

Today the descendants of the Boers who made that pledge of land to Stuurman Ngema, in gratitude for his services as a messenger between them and the warrior Zulu chiefs during the days of their Great Trek into the South African hinterland, are withdrawing it. The government has classified Kwangema as a "black spot" that is "inconveniently located" in the 87 percent of South Africa reserved for white occupation.

The Ngema people have been told that they must go to a resettlement camp about 100 miles away that will become part of a tribal "homeland."

There have been scores of similar removals. South Africa once had many "black spots." In the first few years after Britain gave the country independence under white rule, in a spirit of reconciliation after defeating the Afrikaners in the Boer War at the turn of the century, many blacks tried to take out what insurance they could by buying land.

Pixley Seme, one of the founders of the African National Congress, formed a company called the Native Farmers' Association of Africa, which bought up farms before the white government passed a Land Act in 1913 that prohibited blacks from owning land outside the tiny "native" reserves.

Those who had bought land before then retained their title deeds until the more rigid segregation called apartheid began after World War II. During the past 20 years, Afrikaner nationalist administrations have been using a new law to dispossess the black landowners and move them to the increasingly overcrowded reservations, called "homelands" in the terminology of apartheid.

According to an authoritative study called the Surplus People's Project, more than 3 million black people have been resettled under this and other apartheid programs, and another 2 million are still scheduled for removal.

Some communities, such as Kwangema, have put up a spirited resistance, but a women's civil rights organization called the Black Sash has warned that it believes they are to be moved soon.

That could cause an international outcry. As the world has become aware of the human disruption it is causing, Pretoria's policy of forced removals has aroused widespread protests.

President Reagan made a public issue of it after his meeting with Bishop Desmond Tutu, the Nobel Peace Prize-winner, last month. Sen. Edward M. Kennedy (D-Mass.), who made a tour of South Africa last week, visited Mathopestad, one of the threatened communities, and told the people there that he found the removal policy "inhumane" and "indecent."

Countries of the European Community also are taking a special interest in the removals policy, which became a focus of attention during a rare tour of Europe in June by Pieter W. Botha, then prime minister and now president.

Moses Ngema wrote to Queen Elizabeth II asking her to intercede with Botha when he visited Britain, since King Edward VII had ratified the gift of land to the Ngema people in 1905.

Prime Minister Margaret Thatcher did the interceding when she met Botha June 2. She told him the British government would watch the fate of Kwangema and regard it as the test of his policy of gradual reformism.

The South African government is aware of the price it will pay if it goes through with these removals, but to abandon them would be to deny a fundamental tenet of apartheid that hard-line Afrikaners opposed to Botha's tentative reforms could exploit.

A visit in recent weeks to all the communities thought to be under this imminent threat has been like meeting civilians on the front lines of an impending war. They are full of heart but appear pathetically unequal to the forces ranged against them.

"We won't go," they say, but with little real conviction. Last February police encircled a black-spot farm called Magope in the middle of the night, declared it an "operational area," which meant no one else was allowed to enter, then loaded the inhabitants into trucks at gunpoint.

The government tries to avoid use of force and calls its policy "voluntary resettlement." Foreign Minister Roelof F. Botha explained after meeting with Kennedy last week: "The South African government is against the forceful removal of people, but that must not be confused with removals that must take place, whether they are whites or blacks, for hygienic and medical reasons."

He added, "No government can allow squatting in an uncontrolled way anywhere in the country, just as the Americans would not allow it anywhere in America."

Sheila Duncan, president of the Black Sash, argued: "There is no hygienic or medical reason to move any of the black spots. With their own well-chosen lands to cultivate, the black spots are among the most stable and relatively prosperous black communities in the country."

According to Duncan and her staff, who monitor the removals closely, the government's strategy is either to deal with a compliant chief or to find someone willing to cooperate and appoint him chief.

Officials make it difficult for the communities to stay, the civil rights workers say. They insist that old-age pensions will be paid and work permits issued only at the new place to which the community is supposed to go, which is often a hundred or more miles away. They refuse to build schools and clinics at the old settlements, on the ground that the people are scheduled for removal, then use the lack of these facilities as evidence that the community is undeveloped and not hygienic.

Evidence of attempts to do this can be seen at several of the threatened communities, but where the strategy has failed the government is left with the choice of backing down or moving people by force. That is the point that has been reached at these resisting communities: Kwangema

Although the community has never had a chief, the government has recognized a discredited family member, Cuthbert Ngema, as chief and has been trying to negotiate a "voluntary" removal with him.

According to community lawyers, government officials arranged a community meeting in September, and while most of the people were there, five other men met secretly at Cuthbert Ngema's house and elected him chief. The main body of the community later elected its own council, with Moses Ngema as chairman.

Since then the dispute about the community's leadership has continued, in courts and elsewhere.

Complicating the issue is the government's construction of a large dam that will flood half the Kwangema farm. The authorities did not negotiate compensation with the black landowners, as they do with whites.

The rising waters have started flooding the community graveyard. In an act that caused great distress to these African traditionalists, authorities recently exhumed the remains of the ancestors without ceremony and reburied them in trenches on higher ground.

Yet the spirit of resistance remains. "It will not help them to move us," said Alfred Ngema in frail determination. "If they do, then in the evening our cattle will come back home and we will follow them." Driefontein

This is a community of about 15,000 people living on a 250,000-acre farm bought by Seme's company next door to Kwangema. The residents are to be separated into three groups and resettled in camps in the homeland of Kangwane, 100 miles to the east.

Driefontein's resistance centered on a respected leader named Saul Mkhize. At a community meeting two years ago Mkhize was shot dead by a white policeman, who said at his trial that he was threatened by an angry mob. He was acquitted.

Since then, according to people in the community, government officials have tried repeatedly, but with little success, to persuade chiefs from nearby tribal areas to recruit followers at Driefontein so they can be recognized as having jurisdiction over it.

The community's male elders recently decided, in a deviation from their traditions, to elect Mkhize's widow, Beauty, as their leader.

During a visit last week, Beauty Mkhize pointed out her husband's grave in a little family cemetery beside their home.

"I am going to dig my own grave right there next to Saul," she said, "and when they come I am going to stand in it and tell them that they will have to kill me before I leave."

Then she laughed. Mathopestad

This community, which Kennedy visited Jan. 7, is thought to be the most imminently threatened.

Mathopestad is a rich grassland farm in what is known as South Africa's Maize Triangle, near the western Transvaal town of Koster. It was bought by 22 black families just before the 1913 Land Act was passed.

For three-quarters of a century the community has been able to feed itself and sell a small surplus to the local farmers' cooperative -- no mean achievement in a continent where there is widespread starvation.

But the government says they must go to a resettlement camp in arid bushland bordering the Bophuthatswana homeland, where rows of tin outhouses already await their arrival. The tin toilets are always the first sign that a new resettlement camp is being established.

Three years ago the government was on the point of an agreement with the community's compliant chief, Alfred Mathope, to move them. The communty objected and suspended Mathope as chief, but the government did not recognize the suspension.

Soon afterward Mathope died, and the authorities made a move to recognize his wife, Dorothy, as regent for her 6-year-old son. Dorothy Mathope was willing to go ahead with the resettlement arrangements, but the community objected to her son's appointment as successor, and thus to her appointment as regent, on the grounds that he was an illegitimate child.

They chose Solomon Mathope, 25, instead. Advised by his father John, and strongly backed by the community, Chief Solomon has resisted resettlement.

Abey Ramkoko, 68, a Mathopestad resident, is a lively man who never went to school but who reads the newspapers with a razor-sharp mind.

He acquired his education, he says, by watching movies. For years he was assistant projectionist at a theater in Johannesburg, and he soaked up everything he saw.

Today Ramkoko is a man of means. He belongs to one of the original 22 families who bought the Mathopestad farm and has 5,500 acres under cultivation as his share.

At the resettlement camp, Ramkoko says, he will get "just a little corner," 70 yards by 60 yards. "I ask you, is that the betterment that the government keeps talking about in the newspapers?" he said indignantly. Matiwane's Kop

Eleven black-spot farms near Ladysmith in northern Natal are under threat of removal. The government insists that the 60,000 residents move to an area due for inclusion in the Kwazulu homeland, only 50 miles away but quite different. The farms are in well-watered savannah. The resettlement camps are on stony bushland.

Matiwane's Kop, the lushest of the farms, was bought by the Tshabalala clan late in the last century. Welcome Tshabalala, a descendant, was sitting on the porch of the family homestead recently. He is 38 and bitter.

"Why do you want to tell these western countries about what is happening here?" he sneered. "They just make noises while things go on the same. All this talk and nothing has changed since I was a child. At least the Russians give us the AK47."

Looking out over a scene of idyllic tranquility, he added: "It would be very easy to recruit me for any purpose to bring suffering to the whites. A lot of people here feel that way."