How big was Eden?

This comment got me thinking:-God first mentions Ethiopia in the Creation account itself. The river that watered the Garden of Eden (Gen 2:10) split into four giant rivers: "The name of the first [is] Pison: that [is] it which compasseth the whole land of Havilah, where [there is] gold...And the name of the second river [is] Gihon: the same [is] it that compasseth the whole land of Ethiopia." (Gen 2:11, 13). God's "Garden" was quite colossal, actually -- more like a giant preserve, a country or a continent. His "Garden" had to be watered by a mighty river! That river split into four other mighty rivers, two of which flowed in Ethiopia.