Three people from the Chinese region of Xinjiang killed themselves and two tourists in a "terrorist attack" in Beijing's Tiananmen Square this week, according to police.

Five other people from the area, home to the mainly Muslim Uighur ethnic minority, have also been arrested.

Herewith a factfile on the region's geography, history, people and economy:

Where is Xinjiang and what is its geography?

The vast and resource-rich region -- once a link on the Silk Road -- lies in China's far west and its seven international borders include frontiers with Russia, Afghanistan and Pakistan.

With 1.7 million square kilometres (660,000 square miles) of desert, grassland, mountains, lakes and rivers, it makes up a sixth of mainland China, but the capital Urumqi is around 2,400 kilometres (1,500 miles) from Beijing.

Xinjiang holds roughly 30 percent of China's onshore oil and gas deposits and 40 percent of its coal, along with gold, jade and other valuable natural resources, according to the government website china.org.

The area -- officially called the Xinjiang Uighur Autonomous Region -- is home to ethnic Uighurs, Kazakhs, Kyrgyz and other minority groups.

As of 2011 Uighurs made up 47 percent of the population and Han Chinese 38 percent, according to official Xinjiang figures. In 1949 by contrast Han, China's dominant majority, accounted for six percent.

Has Xinjiang always belonged to China?

Xinjiang -- "New Frontier" in Chinese -- has resisted its rule for most of the past two millennia, but China most recently re-imposed control under the Qing dynasty in the 1870s after defeating Muslim leader Yakub Beg.

Various other groups have sought to establish independence, sometimes playing stronger neighbours such as China, the British Empire and Russia off against each other, and sometimes falling subject to their own internal divisions.

After taking control of China in 1949, the Communist Party launched a military-led programme of Han settlement to secure and develop the region.

Disastrous national policies such as the Great Leap Forward and Cultural Revolution scarred Xinjiang as they did other parts of China and soured ethnic relations.

Beijing today is set on holding on to Xinjiang as a matter of national sovereignty, as a buffer against neighbours and a deep well of energy supplies.

Why are some Uighurs unhappy with Chinese rule?

Rights groups accuse Beijing of imposing tough security measures -- from checkpoints and house raids to disappearances -- in the name of fighting separatism and terrorism.

They say authorities repress Uighurs' Muslim faith by barring them from marking religious holidays or keeping traditions such as women covering their hair.

They argue that Uighurs face discrimination in that regional economic growth mostly benefits the influx of Han Chinese.

Tensions have periodically resulted in violence, which authorities often attribute to "terrorism" and rights groups call individual acts of desperation.

Clashes involving Uighurs and Han in Urumqi left around 200 people dead in 2009. State-run media said 35 people died in a "terrorist attack" by Uighurs in June, and 139 people have been arrested in recent months for promoting jihad.

More incidents may go unreported.

What does China say about the Uighurs' complaints?

Beijing points to its huge development investment as benefiting the region and argues that any government should take tough measures against terrorism.

Xinjiang's economy grew 10.8 percent to 570 billion yuan ($94 billion) in the first nine months of 2013 -- 3.1 percent above the national rate and the ninth-highest increase in the country,the regional government news portal Tianshan said this month.

Investment in "people's livelihoods" and fixed assets reached 123 billion yuan in the period, the party newspaper the People's Daily said on its website Thursday.

Tourism rose 28 percent in the first half of the year to more than 22 million arrivals -- the vast majority of them from within China -- bringing in 24 billion yuan in revenue, according to the official news agency Xinhua.

"Xinjiang enjoys sound economic and social development," foreign ministry spokeswoman Hua Chunying said this week.