Another of those beaten, Satoshi Iwama, said he received five stitches after a blow to the head.

Although protests against forced evictions have become increasingly common in China, the aggrieved rarely succeed in venting their complaints on Chang’an Avenue, the heavily policed artery that passes in front of the Forbidden City, Tiananmen Square and Zhongnanhai, the residential compound of China’s top leaders.

Ai Weiwei, an artist and dissident who joined the demonstration, sent out a spate of Twitter messages detailing the march, which he said made it only about 500 yards before the police intervened.

“It was instinctive,” he said of the decision to protest. “We made a lot of noise, and I think we had a big impact.”

It is unclear whether the protest will force any action against the masked attackers or alter the course of development that threatens at least 10 clusters of studios where artists live and work on the fringes of the city. The clusters, called “artist villages,” house as many as 1,000 painters, sculptors and performance artists.

For two adjacent art districts that were the scene of the early morning protest, known as Zheng Yang and 008, it may be too late. In November, the developer cut off electricity and water, and most of the buildings have already been destroyed.