This is Thailand's "United Front for Democracy Against Dictatorship". 

The, known as the "Red Shirts", are planning mass rally next month in a huge challenge to Prime Minister Abhisit Vejjajiva's

government.

[Jatuporn Prompan, Red Shirt Leader]:

"Our red shirts from all parts of the country will begin to mobilize on March 12th. And all the crowd flows will meet in Bangkok on March

14th"

The group hopes the week long rally will force parliament to dissolve and prompt new elections to be held. 

The Red Shirts back ousted former Prime Minister Thaksin Shinawatra, who is waiting for a Supreme Court ruling on whether or not to seize his assets. 

Thaksin was convicted for graft and was facing other allegations of corruption when he was ousted from office by an army coup in 2006.  He's denied wrong-doing. 

His supporters, the Red Shirts say current leader Abhisit's six party coalition government is "illegitimate" because it was not

elected.

They've been holding numerous smaller-scale rallies over the past few months.