Tibet's transition over the decades has seen its ups and downs. Cui Lingnan looks back at the moments that led to the region's peaceful liberation, the first step towards its reunification with China, and the start of its modernization and economic growth.

This is the symbol of Tibet.

Built more 13 hundred years ago, the Potala Palace has witnessed a vibrant and turbulent history. But one thing hasn't changed, it's always been a part of China.

After the civil war ended in 1949, the Communist Party of China became the sole governing party and authority in the New China. The government formally notified local authorities in Tibet to send delegates to Beijing to negotiate the peaceful liberation of the region.

However, some elite elements in Tibet resisted the idea of unification. They deployed the main body of the Tibetan army in the eastern Qamdo area. Then the People's Liberation Army crossed the Jinsha River and took over the area.

After hostilities ceased, a 17-Article Agreement was signed between delegates of the central government and Tibetan local government. They reached a consensus that regional autonomy would be instituted in Tibet. Existing political system and religious beliefs would be kept as it is.

In October that year, the PLA entered Lhasa peacefully.

Tibet's peaceful liberation brought an end to serfdom, bringing the region into the modern world, while preserving its spiritual traditions. Tibet's economy has advanced quickly along with the rest of the country, with its annual GDP growth topping more than 12 percent since 2000.