The Tanakh mentions another tribe related to the Midianites called Kenites. Jethro, Moses’ father in law was a Midianite, but the Tanakh also describes him as a Kenite. According to a recent book by Prof Robert D Miller II, the term “Kenite" was likely another name for the semi nomadic Midianites who were experts in metallurgy as “Kenite” means smith. Professor Robert D Miller II explained in his book that smiths were often seen as ritual specialists in the ancient world, for example they would perform circumcisions and sacrifices for other tribes. They were influential and seen by others as powerful and even magical so they were both respected and feared. The Midianite Kenites being smiths were in an ideal position to influence the spiritual beliefs of others and in Millers view this is the most likely explanation of how Yahwism spread to the Israelites. Prof Israel Knohl takes a different approach, he suggested that the Israelites and Midianites simply lived in the same areas as each other and this is how the Israelites who originally worshipped El were introduced to Yahwism. He notes the clan of Jacob-el lived near Edom and they could have been the mediators that introduced Yahwism to Israel. 

The Midianites are described in the Torah as helping the Israelites in their years of wandering in the desert after they fled from Egypt. Most scholars say there is no evidence of an Exodus from Egypt as described in the Bible and no evidence of 600,000 Israelites wandering in the area now known as as the Sinai peninsula. If there was an Exodus, the Israelites who left Egypt were not as large as the Torah claims and they may have taken a different route and dwelt in Midian itself rather than the Sinai peninsula as was suggested by the late Prof Frank Moore Cross. Israel Knohl estimated that about 500 people may have left Egypt. 

The cause of the introduction of Yahwism to Israel was likely a combination of some Israelites who were refugees from Egypt dwelling in Midian, intermarriage between Midianites and Israelites who lived in the same areas and the Midianites role as smiths and traders. As a Yahwist, I also see the hand of YHWH in the introduction and spread of Yahwism from Midian to Israel and then from Israel to the rest of the world. 

YHWH Origin of a Desert God, Robert D Miller II

YHWH: The Original Arabic Meaning of The Name, Prof Israel Knohl

A land whose stones are iron and from whose hills you can mine copper, Metallurgy, pottery and the Midianite Kenite Hypothesis, Jacob E Dunn. 

The rise of Yahwism and the role of marginalised groups, Marlene Mondriaan.