The cultivation of the land, which formed the principal source of the wealth of Babylonia,[6] was carried on mainly by slave labour, under the control of the two upper classes of the population. The land itself was largely in the hands of the crown, the temples, and the great nobles and merchants who were landed proprietors; and, including that still in communal or tribal possession,[7] a very large proportion was cultivated on lease. The usual practice in hiring land for cultivation was for the tenant to pay his rent in kind, by assigning a certain proportion of the crop, generally a third or a half, to the owner, who advanced the seed-corn.[8] The tenant was bound to till the land and raise a crop, and should he neglect to do so he had to pay the owner what was reckoned as the average rent of the land, and he had also to break up the land and plough it before handing it back. Elaborate regulations were in force to adjust the landowner's duties and responsibilities on the one hand, and what was due to him from his tenant on the other. As the rent of a field was usually reckoned at harvest, and its amount depended on the size of the crop, it would have been unfair that damage to the crop from flood or storm should have been made up by the tenant; such a loss was shared equally by the owner of the field and the farmer, though, if the latter had already paid his rent at the time the damage occurred, he could not make a claim for repayment. There is evidence that disputes were frequent not only between farmers and landowners, but also between farmers and shepherds, for the latter, when attempting to find pasture for their flocks, often allowed their sheep to feed off the farmers' fields in spring. For such cases a scale of compensation was fixed. If the damage was done in the early spring, when the plants were still small, the farmer harvested the crop and received a price in kind as compensation from the shepherd. But if it occurred later in the year, when the sheep had been brought in from the meadows and turned on to the common land by the city-gate, the damage was heavier; in such a case the shepherd had to take over the crop and compensate the farmer heavily.