One consequence of the new land law was a legal fixation of the social classes. Already during Han time (and perhaps even earlier) a distinction had been made between "free burghers" _(liang-min)_ and "commoners" _(ch'ien-min)_. This distinction had continued as informal tradition until, now, it became a legal concept. Only "burghers", i.e. gentry and free farmers, were real citizens with all rights of a free man. The "commoners" were completely or partly unfree and fell under several heads. Ranking as the lowest class were the real slaves (_nu_), divided into state and private slaves. By law, slaves were regarded as pieces of property, not as members of human society. They were, however, forced to marry and thus, as a class, were probably reproducing at a rate similar to that of the normal population, while slaves in Europe reproduced at a lower rate than the population. The next higher class were serfs (_fan-hu_), hereditary state servants, usually descendants of state slaves. They were obliged to work three months during the year for the state and were paid for this service. They were not registered in their place of residence but under the control of the Ministry of Agriculture which distributed them to other offices, but did not use them for farm work. Similar in status to them were the private bondsmen (_pu-ch'ü_), hereditarily attached to gentry families. These serfs received only 50 per cent of the land which a free burgher received under the land law. Higher than these were the service families (_tsa-hu_) who were registered in their place of residence, but had to perform certain services; here we find "tomb families" who cared for the imperial tombs, "shepherd families", postal families, kiln families, soothsayer families, medical families, and musician families. Each of these categories of commoners had its own laws; each had to marry within the category. No intermarriage or adoption was allowed. It is interesting to observe that a similar fixation of the social status of citizens occurred in the Roman Empire from _c._ A.D. 300 on. Thus in the years between 440 and 490 there were great changes not only in the economic but in the social sphere. The Toba declined in number and influence. Many of them married into rich families of the Chinese gentry and regarded themselves as no longer belonging to the Toba. In the course of time the court was completely sinified.