Tibet in Turmoil

China has launched a crackdown in Tibet after protests and rioting racked the regional capital Lhasa this week. How events unfold will closely involve four key men -- the Dalai Lama and three Chinese officials -- whose backgrounds are explained below:

* The Dalai Lama is the focal leader of Tibetan Buddhism, the religion that binds the vast majority of the mountainous region's traditional inhabitants.

The 14th Dalai Lama, Tenzin Gyatso, lived uneasily alongside the Chinese Communist Party after it sent its army to occupy Tibet in 1950. But he fled on horseback to northern India after a failed uprising against Chinese rule in 1959 and now lives in exile there.

He won the Nobel Peace Prize in 1989.

China accuses him of seeking independence for Tibet. But the 72-year-old spiritual leader says he only wants greater autonomy for his people. China has also accused him of engineering the protests in Lhasa, a claim he has rejected as completely baseless.

* Chinese President Hu Jintao has not publicly commented on the latest unrest in Tibet, but especially with his long experience in the region he is sure to be one of the dominant decision-makers behind the scenes.

A water project engineer by training, Hu spent many years working in Gansu, the western province neighbouring Tibet, and he earned his political stripes in dirt-poor Guizhou and then Tibet, where he was Communist Party boss from 1988 to 1992.

As Tibet's top official, Hu oversaw a harsh crackdown on the last major wave of protests to shake the region in 1988-89. His longtime political patron, the reformist Communist Hu Yaobang -- no relation of Hu Jintao -- fell from office partly because Party elders blamed his more relaxed policies toward Tibet for stoking unrest.

Earlier this month, Hu said that stability in Tibet has a bearing on the stability of China as a whole.

"Tibet's stability has to do with the entire country's stability, Tibet's safety has to do with the entire country's safety," Hu told Tibetan members of the Party-run parliament.

* China's top domestic security official, Zhou Yongkang, has not served in Tibet but will have a powerful say in how the government handles the latest unrest.

Zhou was Minister of Public Security from 2002 to 2007. As the country's top cop, he pushed efforts to combat police abuse and extended detentions without charge. But he also often urged officers to be tough against threats from ethnic separatism.

Last year, Zhou was promoted to the Chinese Communist Party's Politburo Standing Committee, the innermost circle of power. He was placed in charge of law-and-order issues and domestic security, and he also serves on a leadership group overseeing preparations for the Olympic Games that will be held in Beijing in August.

* The current top official in Tibet, Zhang Qingli, is a Han Chinese whose most notable attribute is his complete lack of work experience in Tibet until he was made its Communist Party secretary in late 2005.

Before then, Zhang served for many years in China's other hotspot of ethnic unrest, Xinjiang in the far west, where the largely Muslim Uighur population has bridled under Chinese control.

Zhang rose as an official in the Xinjiang Production and Construction Corps, a sprawling quasi-military network of state farms and factories intended to secure stability in the region by developing the economy and helping control borderlands.

As Tibet's Party boss, Zhang outranks its ethnic Tibetan government chief, Qiangba Puncog. Zhang has taken a notably tough line in Tibet.