Analysts say the sentencing of Ilham Tohti -- a persistent but moderate government critic who spoke out for the rights of the mostly-Muslim Uighur minority -- on charges of "separatism" risks inflaming tensions in the restive Xinjiang region.
"Peace is a gift from the heavens to Uighurs and Han (China's majority race)," Tohti said from prison, his lawyer Li Fangping told AFP. "Only with peace and kindness can we create a better common environment."
"I am brave and I won't be weak," Tohti said, according to Li.
The court's decision -- which includes the confiscation of all his personal property -- has been seen as unusually harsh, and comes amid a broader crackdown on what the state claims is a terror-backed independence movement in Xinjiang.
The sentencing of the 44-year-old drew strong condemnation from the United States and European Union (EU), with both calling for his release.
"They deserve to be free. They ought to be released," he said. "This growing crackdown on civil society is a campaign to undermine the very idea of democracy."
Separately, the White House urged Chinese authorities to differentiate between "peaceful dissent and violent extremism".
"We believe that civil society leaders like Ilham Tohti play a vital role in reducing the sources of inter-ethnic tension in China, and should not be persecuted for peacefully expressing their views," a statement said.
The EU called the sentence "completely unjustified" and urged his immediate and unconditional release, echoing separate statements from countries including Britain and Germany.
