ZHANGBEI, Hebei -- "If you don't rock, just roll away!" says a flag waved by Ai who, at the same time, moved his body to the heavy beats and rhythms of rock music, along with thousands of other rock fanatics in the grasslands of Zhangbei, a small and underdeveloped county in north China's Hebei province.

Hundreds of thousands of people flocked to Zhangbei's grassy fields over the weekend, just two-hours drive outside Beijing, to enjoy music and release their energy and passion at the 2nd InMusic Festival, which is also known as China's "Glastonbury."

The 20-year-old Ai, who is a confessed rock-and-roll addict, purchased the tickets a month ahead of the three-day festival, which opened on July 30. He came from Beijing with a dozen friends.

"We are here just to let off steam, which the big cities have no room for," he said.

"With teachers and parents not being around, it will be so much fun," he said, smiling.

Pitched tents, smoking barbeques and small markets selling T-shirts, CDs, and other souvenirs, were scattered throughout the 100-hectare grassy festival site.

Apart from the music, the big open skies and overnight camping on the vast fields offered visitors a chance to spend the weekend outside big cities like Beijing, said Liu Yifan, producer of InMusic magazine, which co-sponsored the music fest with Zhangjiakou Tongtai Transportation Corp, Beijing-based Pilot Records and the Zhangbei government.

This year, organizers are expecting 200,000 attendees, as more than 150,000 people were here last August to enjoy a getaway weekend in music when the annual festival rocked Zhangbei's grasslands for the first time.

To satisfy the fevered rock fans, the InMusic Festival, which features more than 50 Chinese and foreign bands and singers spanning metal, punk, folk, electronic and hip hop, ended very late, at 2 a.m., each night.

Famed Chinese singers Zheng Jun and Lao Lang performed during the fest. Foreign acts include US pop-rockers Panic! At The Disco, Paris-based American duo CocoRosie and British post-punks Killing Joke.

Nearly 1,000 security workers, including police officers, firefighters and civil servants, kept a watchful eye on the excited crowds.

"It's quite amazing if you imagine that some 200,000 people suddenly show up on a grassland that rarely has people around and then they disappear three days later," said Zhang Heng, a twenty-something woman who came to the festival to - in her words - "go crazy." The county only has 130,000 permanent residents.

Despite all the excitement, some attendees complained about the unpredictable weather and traffic jams on roads leading to the site.

Rain hit the county Saturday, which made the grassland very muddy and ruined many attendee's shoes and clothing.

Meanwhile, nighttime on the grassland was cold for many campers. Besides, roads leading to the site were very narrow, therefore extremely crowded as many drove their cars to enjoy the festival.

Zhangbei, an economically poor county, had little fame before last year's 1st InMusic Festival.

Local residents joked that the festival was the third time that the nation had paid attention to this small county, including following a magnitude-6.2 earthquake that killed 49 people and injured more than 10,000 in 1998 and when President Hu Jintao visited in 2004, during which he made dumplings with villagers.

Click rates of online news stories about last year's festival stood at 30 million viewings, the Zhangbei government said in a report.

The local government thought hosting a music festival would prove to be a good method of self-promotion, as the county needs publicity for its grasslands tourism, according to Li Xuerong, Zhangbei's Communist Party chief who said he got the inspiration and information about holding the event from friends in Beijing.

Previously, the county government tried to promote Zhangbei in various ways, but all had little effect, he said.

Also, local residents knew the festival would be a good opportunity to make money through selling food, water and accommodations.

More than 60 booths supplying food and water were set up at the site.

Some local families also turned their homes into temporary hotels, where they shared with guests all that they had.

Last year, the county's service industry grossed more than 12 million yuan ($1.76 million) during the three-day music carnival from August 7 to 9, according to data from the county's commerce and tourism bureaus.

"We earned about 30,000 yuan during last year's festival," said Wang Shulan, 56, who owns a farmhouse restaurant near the festival site.

These numbers were not too small for a county in which the average income for farmers in 2009 was only 2,954 yuan, just above half of the national average.

"The music festival has become a brand for the county. Possibly, it could last for more than ten years, as the government has reserved lands as big as five times the current site for future events," said Liu Yifan, producer of InMusic Magazine.

The Zhangbei government and InMusic signed a 10-year contract to jointly organize the music festival during each of the next 10 years.