Ethnic Mongolians in northern China have held a rare protest in front of a government building over the death of a shepherd.
Crowds of students this week marched to the building in Xilinhot, a city in Inner Mongolia, rights groups said.
They were angry at the 10 May death of a herder, Mergen, who they say was run over by a van driven by a Han Chinese, the country's dominant ethnicity.
The Xilinhot government has not commented on the protest.
In a statement on its website, though, the government said police had arrested two Han Chinese for murder.
China's six million ethnic Mongols say their nomadic pastoral existence is being threatened by the growth of mining projects in the mineral-rich region.
One local resident told the BBC the Mongols' basic living environment "is being destroyed".
"In the past Mongolian herdsmen seldom held protests, but now they are rising up because the damage to the grassland is so serious, plus the desertification, lack of rain that it is becoming intolerable," said the resident, who did not want to be named.
The New York-based Southern Mongolian Human Rights Information Centre said 2,000 students had taken part in the protest, which was the latest in a series of demonstrations since the shepherd's death.
The demonstrations aimed "to urge the Chinese authorities to respect the rights and dignity of Mongolian herders" in Inner Mongolia, said the group in ia statement.