וְשֵֽׁם־הַנָּהָ֥ר הַשֵּׁנִ֖י גִּיח֑וֹן ה֣וּא הַסּוֹבֵ֔ב אֵ֖ת כָּל־אֶ֥רֶץ כּֽוּשׁ׃
And the name of the second river is Gihon; the same is it that compasseth the whole land of Cush.
Read Jewish philosophical commentary on Genesis 2:13: and classical philosophical sources.