The first known mention of Yahweh outside the Bible is from certain inscriptions at Khirbet al-Qom and Kuntillet Ajrud, which refer to him by this name, dating from the period of Iron Age II (850 BCE - mid 9th century). The Kuntillet Ajrud inscription is significant as it shows Yahweh was not a monotheistic God at this time, as the inscription refers to "Yahweh and his Asherah" (as his Goddess).
Asherah, is of course the Goddess of the Groves, whose sacred trees were destroyed by order of Josiah, just before the fall of Jerusalem to the Egyptians (in which Josiah was killed) and immediately after to the Babylonian forces of Nebuchadnezzar. She elsewhere was called Athirat - and was, in the Late Bronze Age, called wife of El, mother of the Gods. It would seem that by the era of the Kuntillet inscription Yahweh had displaced El as Asherah's husband.
The first mention of the full name of Yahweh occurs in an Egyptian context . In the reign of Amenhotep III (1382-1344 BCE, 9th King of the 18th Dynasty), in the Late Bronze Age (i.e. 1550-1150) we have a reference to Yahweh of the Shasu, in which, from the context it would seem that they were referring to a mountain shrine by that name. Shasu is the Egyptian word for "wanderers" and was used for nomadic pastoralists. Whilst there is no earlier mention of Yahweh than this, there is mention in the region of a God called variously Yaa, Yaw, or Yah, and at Ebla (2,200 BCE) there is occurrence of names in which Yah is used as a theorphoric element (i.e. God's name) in the names of certain people. For instance the name Micha-el, (where the El referred to El, the Canaanite "Father of the Gods", later accepted by the Bible as another name for Yahweh), would be found written as Micha-yah.
This change seems to have coincided with the period in which Western Semitics (from which Hebrew later developed) first came in contact with the Mesopotamian theology of two gods - Enlil, the King of the Gods (who was corelated with Western Semitic El), and Enki, called Ea, the creator of humankind, who saved humans from the flood (who was correlated in the Western Semetic tradition with Yah). It was the wisdom of Yah (Yah-hwh) that came together to form the amorphous God Yahweh (shown at Kuntillet Ajrud, as an androgenous being - both male and female).
Although Yahweh was named, he was not monotheistic until the 2nd temple period. We have letters from the Jewish Temple at Elephantine to the Jewish temple at Jerusalem, speaking of Yahu and his consort, the goddess Anat. And there is no indication that the Jews of Elephantine were condemned by the Jerusalem temple in any way for worshipping a God and Goddess. Monotheism as the dominant Jewish belief system thus came in the period of the 2nd temple. It was not present in 1st Temple Monarchial times, when Yahweh was only one God amongst many .
There were two montheistic gods before Yahweh - firstly the Egyptian son of Amenhotep III, the Pharaoh Akhenaton, worshipped the Aten alone, as a monotheistic divinity. This God, whose name means "disk" in Egyptian was symbolised as the solar disk with rays ending in hands holding the gift of life (the Ankh).
The Persians also adopted a monotheistic religion worshipping their God Ahura Mazda (= Wise Lord) from their prophet Zarathushtra. This God was like Yahweh, a fusion of the spirit of God (Ahura, Sanscrit Asura) with wisdom (Aramaic HWH, Iranian Mazda). There is much that began in Zoroastrianism, eg. the presence of a devil, the worship of angels, the idea of a "last judgement", the concept of a Saviour, the portrayal as angels with wings and haloes; that was adopted by later 2nd Temple Judaism from the Persian (Iranian) source . Also from an Iranian source, was the idea of a saviour, born in midwinter, in a cave or stable, surrounded by farm animals, and attended by Magi. These elements clearly influenced the development of the Christian traditions about Jesus.
Watchtower misled us into praying to a god who is not only unoriginal but who doesn’t even exist!