A camp of olive-green tents and two rings of roadblocks surround this sanctuary of meditation. Local people say the monks pay the army for food to be sent to them.
Drepung was singled out for punishment and “re-education” because Chinese security forces identified many of its monks on video recordings of the protests against Beijing’s policies in Tibet.
The Nechung monastery, about a mile south, was also sealed off. Tibetans said its monks were known for their fidelity to the Dalai Lama.
Although pictures of him are banned, the exiled spiritual leader of Tibetan Buddhism still exercises an uncanny grip on his people that half a century of Chinese propaganda has failed to break.
Modern Chinese rhetoric omits to say that the Dalai Lama, then a very young man, did his best to co-operate with China when its troops entered Tibet in 1950. He fled to India in 1959 after communist policies set off an uprising among the Tibetans.
The Dalai Lama himself has always condemned violence. He says he does not want independence but genuine cultural and religious autonomy within China. The Chinese say they do not believe him.
That is why control over the religious life of Tibet is crucial to Chinese rule.
Drepung may be a fortress of resistance but across Lhasa the picture varies. Some monasteries have complied with Chinese officials and installed party-controlled committees, allowing them to pursue their Buddhist studies in troubled silence.
One pleasing result for the authorities can be found at the Sera monastery in north Lhasa, whose 500 monks did not join the protests and have collaborated in the formation of an “administrative committee” to supervise them.
“We now study the Chinese constitution, the law against separatism, the law against demonstrations, the criminal law and other documents requiring us to love the motherland, love the government, support stability and understand the real intentions of the Dalai Lama,” said a monk named Chamba.
Tibet was reopened to foreign tourists on June 25. Compared with foreign diplomats and journalists, who have been admitted only on short, tightly controlled tours, tourists have been able to circulate with relative ease.
Accounts from travellers paint a picture of frightened Chinese residents protected by bored soldiers, while Tibetans are divided between government employees loyal to China and a majority of sullen, resentful people.
Economic growth, fast and furious under Chinese stewardship, has deepened some of the divisions. Most taxis are driven by Han Chinese; most rickshaws are pedalled by Tibetans.
Superficially, coercion appears to be working. On the road to Lhasa from the airport, every Tibetan farmhouse flies the red and gold Chinese flag. Sentries are posted on bridges and outside official buildings.
On every street corner in the city centre, a soldier stands watch. Most temples and monasteries are under 24-hour surveillance.
“I began to realise that Tibetans hate the Han [Chinese] from their bones and their hearts,” said a shopkeeper who migrated to Lhasa from Shanxi province in central China. “They are a very strange nation. They do not care about material things but only about the spirit.”