<< A huge silk portrait of the Sakyamuni Buddha is unveiled at the start of the week-long 'Yogurt' Festival in Lhasa.AP

Many had walked hours to the Drepung Monastery for the beginning of the seven-day Shoton or ''Yogurt'' Festival. As a massive 35-by-30-meter silk embroidered image of the Buddha was unfurled across a hillside, celebrants threw white Tibetan scarves into the air and took pictures with their cell phones.

Scores of Chinese police kept watch over the crowd in this restive, independence-minded region. They videotaped the proceedings from the roof the monastery and barked at those filing past the Buddha's silken image to keep the lines moving.

China says it has ruled Tibet for centuries, but Tibetans say they were independent for much of that time. The leader of Tibetan Buddhism, the Dalai Lama, fled to India in 1959 during a failed uprising against Chinese rule.

``Our Tibetan traditions reach far back into history, and we bring our children here every year so they understand these traditions,'' said Qu Yong in halting Chinese as her 10-year-old daughter and two nieces, 12 and 15, giggled behind her.

``They need to understand Tibetan culture and remember it always.''

As many as 40,000 people come each year to the festival at Drepung Monastery, which is home to about 300 monks. Thursday, they jammed into its prayer halls, lined up for cups of yogurt and set up picnic lunches on the rocky hillside. The Yogurt Festival gets its name from a practice of centuries' past when herders would bring pots of yak-milk yogurt to monks who had been fasting within the monastery's walls.