There existed three types of land in ancient Rome: private land, common pasture, and public land. By the 2nd century BC, wealthy landowners had begun to dominate the agrarian areas of the empire by "renting" large tracts of public land and treating it as if it were private. This began to force out smaller, private farmers with competition; the farmers were forced to move to the cities for this and a number of other factors including battles making living in rural areas dangerous. Roman cities were not good places to attempt to get jobs; they were also dangerous, overcrowded and messy.
In 133 BC, Tiberius Sempronius Gracchus, the plebeian tribune, passed a series of laws attempting to reform the agrarian land laws; the laws limited the amount of public land one person could control, reclaimed public lands held in excess of this, and attempted to redistribute the land, for a small rent, to farmers now living in the cities.
Further reforms in 122 BC were attempted by Tiberius's brother, Gaius Sempronius Gracchus, including the expansion of the laws' area of influence to all of the colonies in Italy. These reforms, however, were not as successful due to massive unpopularity in the Italian provinces.
By 118 BC the sales limits and redistibution efforts had been abolished, and by 111 BC the laws were standardised, confirming the positions of many owners in Italy about their large tracts of land.