The Abbai portion of the river is considered holy by many in Ethiopia, and is believed to be the Gihon river mentioned as flowing out of the Garden of Eden in Genesis 2. The Abay portion of the Blue Nile rises at Lake Tana and flows for some thirty kilometers before plunging over the Tis Issat Falls. The river then loops across northwest Ethiopia through a series of deep valleys and canyons into Sudan, by which point it is only known as the Blue Nile.