They headed for Toulouse in the early morning light, honking horns and pulling trailer-loads of hay and manure as they moved in on the ancient city center, blocking entire lanes on some roads and causing massive traffic jams.
Bus services were forced to change their routes and the local police chief called on residents to avoid central Toulouse.
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When the tractors reached the regional authority building, they tipped dozens of trailer-loads of rotting fruit, hay, and manure right in front of it.
Around 1,000 farmers gathered on the central Capitole square on foot, and a delegation was expected to meet the local police chief later in the day.
The protesters say increased taxes and social charges are causing hardship for farmers across the region. The tax hikes and other fees come on top of increased costs for fuel and animal feed, and a general rise in the cost of living across the country.
Elsewhere in the region, farmers targeted large suburban supermarkets, dumping manure in their parking lots. The farmers say many big supermarket chains refuse to pay fair prices for their produce.
Tuesday's protests followed a number of demonstrations in the region last November, as farmers fear for their livelihoods.
Comment: Farmers across Europe are sounding the alarm that the attack on their livelihoods, which is the people's food supply, is reaching a breaking point: 30,000 attend 7th day of farmer protests in Germany, truckers & farmers protest for 5th day in Romania