Gyalo Thondup was born in 1928, more than three decades before the 1959 revolt in Lhasa against Chinese forces, whose crushing forced the Dalai Lama across snowy Himalayan passes into India.

He later led the Tibetan government in exile as chairman of its "Kashag" or cabinet in the early 1990s, and was the personal emissary of the Dalai Lama.

The Dalai Lama, speaking Sunday in prayers at the Tashi Lhunpo Monastery in southern India, said elder brother "did his best, and was very dedicated and brave".

The spiritual leader offered prayers "for the fulfilment of the deceased's wish to be able to work closely with the Dalai Lama for the Tibetan cause in all his future lives".

Thondup died in India on Saturday evening.

The fading generation of Tibet leaders -- especially those who can remember what their homeland was like before the 1959 uprising -- raises worries amongst many in the diaspora for the future.

The 89-year-old Dalai Lama says he has decades yet to live, but Tibetans who have followed him abroad are bracing for an inevitable time without him.

China says Tibet is an integral part of the country, and many exiled Tibetans fear Beijing will name a rival successor to the Dalai Lama, bolstering control over a land it poured troops into in 1950.

- 'The world is changing' -

Tibet has alternated over the centuries between independence and control by China, which says it "peacefully liberated" the rugged plateau and brought infrastructure and education.

The International Campaign for Tibet group said Thondup was the "point person to take up the Tibetan issue internationally" after the Lhasa uprising.

He was also key among those who reached out to the CIA for supplies to a 2,000-strong force to launch guerrilla attacks against Chinese forces as a Cold War proxy.

During the 1960s they snuck into Tibet from Nepal's mountainous kingdom of Mustang to lay ambushes, including blowing up Chinese army trucks.

But after the CIA cut funding, and the Dalai Lama in 1974 urged fighters to lay down arms, the fighters and Thondup followed his call for a peaceful solution.

Thondup, speaking in 2008, is quoted as saying that he hoped China would take a more "reasonable approach and treat us equally".

Despite little sign of policy shifts from Beijing, including rounds of negotiations in which he had a major role, he said he had not lost hope for a peaceful resolution.

"Have you ever dreamed? China is changing, the world is changing," he said.

"I'm quite optimistic".