Birthplace of the Tigris in ancient times, that is, Birkleyn caverns.
The place where Birkleyin Suyu (Birkleyin Waters) flow underground through a natural tunnel before surfacing, is called Birklyen or Tigris Tunnel. In the Ancient Period, the place where these waters disappear flowing underground was defined as “end of the world”. Pilinius himself defined this waterway as “the place where the dead pass to the underworld”.
There are three caves inside these rocks, formed in paralel to one another. 3 embossments and 5 cuneiform tablets from the Assyrian King Tiglatpileser I (1114 - 1076 BC) and Salmanasar III (859 - 829 BC) can be found in the cavern that runs Birkleyn Waters, located under the southern rocks.
On one of the tablets, Assyrian King Salmanasar III says:
O’ mighty gods, blessing my kingdom, dignifying my name
Assur, Bêl, Sîn, Samas, Adad, Istar.
Salmãnu-asarêd (Salmanasar III), king of four universes, King of Assyria,
Son of Assur-nãsir-apli (Asurasirpal II), King of Assyria,
Son of Tukultî-Ninurta, King of Assyria Nairi Country (= Lake Van)
The sovereign conqueror, from the great (sea) (=the Mediterranean) where the Sun sets.
I have conquered the Hatti lands inch by inch. I entered the Enzu passage. I have
conquered all Suhmu Daiãnu and Urartu lands totally. I have entered the Gilzanu
lands, accepted the taxes of the Gilzanu. I have been to the Nairi lands
thrice. I have scripted my name on the source of the Tigris.