Jellinek thinks (l.c.) that there were several haggadic midrashim to Canticles, each of which interpreted the book differently, one referring it to the exodus from Egypt, another to the revelations on Mt. Sinai, and a third to the Tabernacle or the Temple in Jerusalem; and that all these midrashim were then combined into one work, which, with various additions, forms the present Shir ha-Shirim Rabbah.
The Judean sources, the Yerushalmi and the haggadic midrashim, introduce baraitot from this Mekilta with the phrase, "Teni R. Shim'on" = "R. Simeon has taught" (comp. Friedmann, introduction to his edition of the Mekilta, pp. 55 et seq.; Hoffmann, l.c. p. 48).