Out of this original division an awkward situation soon arose. The tribes of the Albans ( Ramnenses ) and the Sabines ( Tatienses ) remained always in the same condition, while that of the foreigners ( Luceres ) continually grew as more and more foreigners came to live at Rome, so that it soon surpassed the others in strength. Servius remedied this dangerous fault by changing the principle of cleavage, and substituting for the racial division, which he abolished, a new one based on the quarter of the town inhabited by each tribe. Instead of three tribes he created four, each occupying and named after one of the hills of Rome. Thus, while redressing the inequality of the moment, he also provided for the future; and in order that the division might be one of persons as well as localities, he forbade the inhabitants of one quarter to migrate to another, and so prevented the mingling of the races.