Matsyapurana 114.12

114.12

brāhmaṇāḥ kṣatriyā vaiśyā madhye śūdrāśca bhāgaśaḥ
ijyāyutavaṇijyādi vartayanto vyavasthitāḥ //

The Brâhmaṇas, the Kṣatriyas, the Vaiśyas, and the Śudras inhabit in its centre and carry on (i.e., inside this boundary) their occupations of rituals (sacrifice, &c.) trade, commerce, &c.—12.