For a full account of the early contests between the Bráhmans and the Kshattriyas, see Muir's Original Sanskrit Texts (Second edition) Vol. I. Ch. IV.
“Ambarísha is the twenty-ninth in descent from Ikshváku, and is therefore separated by an immense space of time from Triśanku in whose story Viśvámitra had played so important a part. Yet Richíka, who is represented as having young sons while Ambarísha was yet reigning being himself the son of Bhrigu and to be numbered with the most ancient sages, is said to have married the younger sister of Viśvámitra. But I need not again remark that there is a perpetual anachronism in Indian mythology.” Schlegel..
“In the mythical story related in this and the following Canto we may discover, I think, some indication of the epoch at which the immolation of lower animals was substituted for human sacrifice.… So when Iphigenia was about to be sacrificed at Aulis, one legend tells us that a hind was substituted for the virgin.” Gorresio.
So the ram caught in the thicket took the place of Isaac, or, as the Musalmáns say, of Ishmael.
Sítá means a furrow.
“Great Erectheus swayed,
That owed his nurture to the blue-eyed maid,
But from the teeming furrow took his birth,
The mighty offspring of the foodful earth.”
Iliad, Book II.