[3] From its source in the Ethiopian Highlands near Mizan Teferi it flows to the west, through Lake Tata to join the Pibor River on Ethiopia's border with Sudan.

The river valley was subjected to much prospecting for gold before World War II and in the 1950s, but not enough was found to make commercial extraction viable.

McMillan's expedition that traveled through this part of southwestern Ethiopia in 1904, estimated its length at 200 miles and noted that at flood the width of the Gilo reaches 80 to 100 yards, with a depth of about 20 feet.

Jessen further wrote that at the time of his visit: The river abounds with fish, and as a natural consequence, the crocodiles are very numerous and large.

It is a remarkable fact that the hippopotami are conspicuous by their absence, only one having been seen and killed many years ago, as these animals are plentiful everywhere in these countries.