The Dalai Lama has renewed calls for autonomy in Tibet as the country marks 50 years of revolting against Chinese rule. Speaking before some 10,000 Tibetans from the main Buddhist temple in Dharamsala, India, the 73-year-old leader slammed China for bringing "untold suffering and destruction" to Tibet and turning the region at times into "hell on earth". But he said the two sides must find a way forward together. He said: "From time immemorial, the Tibetan and Chinese peoples have been neighbours. We Tibetans are looking for a legitimate and meaningful autonomy." A minute's silence was observed in the memory of victims of last year's Chinese crackdown in Tibet, and shortly after his speech, thousands of Tibetans marched through the Dharamsala carrying "Free Tibet" posters and protesting against a new Chinese security clampdown. Border controls have been tightened in Tibet and ethnic Tibetan areas in neighbouring provinces of China to prevent anti-Chinese protests during the anniversary. Meanwhile, Chinese President Hu Jintao has warned his government would not relax its control of the mountain region Mao Zedong's Communist forces took in 1950, calling for "a sturdy Great Wall against separatism". He told Tibetan leaders in Beijing that China's "unity" needed to be protected and Tibet's long-term security secured. His warning comes as two home-made bombs exploded in a Tibetan part of west China. No injuries were reported, but the blasts damaged a police car and another vehicle in Qinghai province. Last year, protests in Lhasa to mark the anniversary led to the worst unrest in Tibet regions for two decades.