Targum zu Bamidbar 2:3

The length of the camp of Israel shall be twelve miles, and its breadth twelve miles. And they who encamp eastward to the sunrise shall be of the standard of the camp of Jehudah by their hosts, spreading over four miles. And his standard shall be of silk, of three colours, corresponding with (those of) the precious stones which are in the breastplate,--sardius, topaz, and carbuncle; and upon it shall be expressed and set forth the names of the three tribes of Jehudah, Issakar, and Zebulon; and in the midst shall be written : Arise, O Lord, and let Thine enemies be scattered, and Thine adversaries be driven away before Thee; and upon it shall be set forth the figure of a young lion. And the Rabba of the Beni Jehudah shall be Nachshon bar Amminadab.