To the staccato rhythm of drumbeats and the wordless religious chants of their ancestors about 1,000 American Indians marched to the Capitol yesterday to ask for justice for their people.

They had come hundreds, perhaps thousands, of miles from all across the country before gathering in native dress for a stately half-hour march from the monument grounds to the west front steps of the Capitol.

As the Indians and their supporters marched along the mall toward the Capitol, there arose a periodic cry from an Indian leader; then there was the steady sound of drumbeat and chanting until all the marchers had reached the steps, historic meeting ground for demonstrators.

Yesterday's march and rally were the first of three days of demonstrations at the three branches of the U.S. government. Today the Indians plan to march on the Supreme Court, and Wednesday they will march on the White House and rally in Lafayette Park.

Indian leaders, said they came to ask Congress not to approve pending legislation that they fear will take away their lands. They said they also wanted to demand that the government live up to prior agreements to allow them to exist an Indian nations with control over their own culture, education and destinies.

"We've come here to ask the government to guarantee our rights to traditional fishing areas, to certain national lands that have been set aside for us," said Vernon Bellecourt, an Ojibwa Indian from Minnesota who is one of the march's national coordinatiors.

"We have come here, to this American government, for 200 years to try and reason with these people," he said. "We have brought our people together. It is positive and it has given us courage."

Some Indian leaders and park police had estimated that the crowd would swell to 2,000 to 3,000 people. But many of the Indians, especially young children and the elders, remained at a special campsite for them in Greenbelt Park in Prince George's County, where the Indians have asserted effective control and authority over their 600-acre encampment.

At the head of the procession of Indians, five emotionless chiefs and spiritual leaders in full regalia set the pace and tone for the march as other Indian officials and guards raced from side to side talking to each other with walkie-talkies. They also kept in touch with an Indian representative stationed at the D.C. police headquarters radio communication room.

The marchers were dressed in traditional eagle feather headdresses, beaded chokers and multicolored, multiprint shirts and dresses. Some wore moccasins, cowboys boots and jogging shoes. Others wore no shoes or shirts.

Bellecourt said, "These people are determined to see (President Jimmy) Carter. He sees the Campfire Girls, and the Boy Scouts, he should see us too."

Clan mother Audrey Shen, an Onandaga Indian, came dressed in a red overshirt so that members of her clan could see her. In the Indian culture, a matriarchal culture, it is the clan mother's responsibility to select the chiefs who represent the clan as tribal council, he said.

Indian leaders at the Capitol steps spoke of promises made, but never kept.

"In the beginning, our chiefs stuck out their hands in friendship and ended up having to fight," said Oren Lion, one of the leaders. "Freedom was the greatest gift that we gave to our brothers who came across the water - they did not know what freedom was. Now they want to take away our freedoms."

One leader, Larry Red Shirt, said "all of us are facing the same problems - fishing rights violations, strip mining, it goes on and on. We've seenthe elders come time and time again to Washington to talk about treaty rights."

Others talked about an Indian "manifesto," to be issued soon, that will call for, among other things, a $300 million damage suit alainst the Bureau of Indian affairs "for sterilization of thousands of our Indians brothers and sisters." There was no immediate explanation.

Meanwhile at Greenbelt, the Indians have asserted control over their encampment in the southern sector of the 1,100-acre park, manning check-points, determining who may enter and maintaining internal governance.

The unusual arrangement, by which even the U.S. Park Police have agreed not to enter the camp unless asked to by the Indians, was developed at the highest levels of the Interior Department and its National Park Service. It has its roots, according to Interior officials, in long-standing treaty agreements with the Indians and a government trust relationship providing for special consideration for native Americans.

Some Interior officials also acknowledge privately that flexibility, rather than by-the-book rigidity, was a more practical way to avoid possible confrontation with militant elements within the Longest Walk and rhetorical claims that they are the "original landlords" of U.S. lands and were "coming here anyway."

The net effect is that Indians - rather than Park Service rangers - run the camp. Checkpoints are jointly manned by rangers and Indian security guards, but the Indians decide who may enter, where trucks with food and equipment may go, when portions of the camp will be sealed off entirley to the public for private Indian religious ceremonies.

The Indians and an adjacent "support-camp" of whites and other non-Indian activists will be in Greenbelt for the rest of the week.

The arrangement giving control of the Greenbelt camp to the Indians is similar to that for the Poor Peoples Campaign here 10 years ago, when thousands of blacks and other minorities set up a plywood and canvas camp called Resurrection City in West Potomac Park near the Lincoln Memorial and Reflecting Pool.

Entrances were controlled by so-called Tent City Rangers from the Poor Peoples Campaign and police were not allowed to enter.

The Interior Department agreement to Ressurrection City, however, was not rooted in historical treaties but more in a practical effort to minimize further civil disruptions in the wake of the assassination of civil rights leader Martin Luther King Jr. and the widespread urban riots triggered by his death in 1968.

For the Indians here in 1978, autonomy at Greenbelt Park "is a direct outgrowth of treaties of the 1860s and 1870s." said Bureau of Indian Affairs spokesman Tom Oxendine yesterday, "Under most treaties between the government and the Indians, the idea was "You doyou thing, and we'll do ours."