FACTBOX: Who are the Tibetans, what is Tibet?

March 21 - Tibetans in China's southwestern province of Sichuan said on Friday they believed several people had been killed in anti-Chinese riots there this week, disputing official claims none had died in the restive region.

Here is some background about Tibet and the Tibetan populations living in neighboring Chinese provinces.

TIBETANS:

-- Mostly Buddhist Tibetans have lived on remote, high-altitude plateaus and grasslands by the Himalayas for centuries. Hundreds of thousands still follow a nomadic lifestyle, raising yaks, sheep, goats and horses on grasslands.

-- Generally calling themselves "Bodpa", they speak dialects derived from the written Tibetan language.

-- Tibetans have been formally classed as one of China's 56 ethnic groups since Chinese troops were sent in 1950.

TIBET'S HISTORIC BOUNDARIES:

-- Bordering India, Nepal, Bhutan and Myanmar, Tibet's boundaries have changed over the centuries.

-- Known as the "land of snows" and the "roof of the world", it is ringed by mountains -- the Himalayas to the south and the Kunlun mountains to the north.