before carnaval was what it is today and back when the sambódromo didn't exist, rio's carnival was all about blocos.

blocos dos sujos (street parties of the dirty ones) are the blocos that still mostly resemble the original celebrations.

blocos are a street party with a band parading and people marching behind it, usually organized by communities, neighborhood associations, or by groups created specifically for the purpose.

called 'carnaval de rua' (street carnival) to distinguish it from the the carnival of the parades, rio's street carnaval is still made up of hundreds of blocos, much more organized today than their original version when all neighbors needed were a drum, a barrel or even an old trumpet to get the party started.