After the 1989 Tiananmen Square protests and massacre, Tang fled from agents of the Chinese Communist Party (CCP) who eventually arrested him in the city of Jiangmen.

Upon his release, he fled to Hong Kong, where he co-authored the report Anthems of Defeat: Crackdown in Hunan Province 1989 - 1992 through Human Rights Watch with Dr. Robin Munro of the University of London.

In June of that year, at a press conference in Washington, D.C., he announced the existence of an underground group called the All-China People's Autonomous Federation.

According to Tang, the Federation was, at that time, operating in the People's Republic of China, and consisted mostly of former students who had taken part in the Tiananmen Square protests of 1989.

Among these were the plight of three Chinese dissidents sentenced up to life imprisonment for hurling paint at an image of Mao Zedong in connection with student protests during the 1989 democracy movement.

In particular, he has called for a reassessment of China's human rights policies (including the number of actual casualties sustained in the Tiananmen Square massacre), an examination of the persecution of Falun Gong practitioners worldwide, support for the Dalai Lama's efforts to negotiate change for Tibet, and an end to the Chinese Communist Party.

Tang noted that the reform efforts of Zhao Ziyang, Bao Tong, and Chen Yizi might well have prevailed had the crackdown never occurred.