Kommentar zu Divrej Hajamim I 1:13

And Canaan begot, etc. They are eleven, and with Canaan they are twelve. This is what is written: “He set up the boundaries of the peoples.” He set up the boundaries of the peoples corresponding to the tribes of Israel, for they too are twelve; corresponding to the tribes of Israel, He set up the boundaries of the peoples, on the pattern of (Gen. 21:29): “... that you set up (הִצַּבְתָּ) by themselves.”