Beginning in 2008, there was worsening conflict between the People's Alliance for Democracy (PAD) and the People's Power Party (PPP) governments of Prime Ministers Samak Sundaravej and Somchai Wongsawat. It was a continuation of the 2005–2006 political crisis, when PAD protested against the Thai Rak Thai (TRT) party government of Prime Minister Thaksin Shinawatra. PAD followers usually dressed in yellow, yellow being the royal color of King Bhumibol Adulyadej, and were called "yellow shirts". National United Front of Democracy Against Dictatorship (UDD) followers, known as supporters of the deposed prime minister Thaksin Shinawatra, dressed in red and were widely called "red shirts".

The People's Alliance for Democracy is a Thai reactionary, monarchist political movement and pressure group. It was originally a coalition of protesters against Thaksin Shinawatra, the former Prime Minister of Thailand.