"Biblical Monotheism" arose, supposedly, from the Josianic religious reforms of the 7th c. BCE (largely outlined in Deuteronomy). Remember, though, that these religious reforms were literary and likely hard to enforce on the ground. Popular religion and religious practice persisted, of course.

A few good sources:

Mark Smith, The Early History of God (MUCH better and much more professional/authoritative than Karen Armstrong's popular book on a similar [read: NOT THE SAME] topic).

Bodies of God by Benjamin Sommer discusses the issue of local manifestations of deities, etc.

Because I contributed quite a bit to the discussion on antediluvian life-spans yesterday, I'm also going to copy/paste here my answer I gave on my Religions of Israel comprehensive PhD exam question. (Because I'm tired.) The question asked about epigraphic (read: inscriptions) evidence for ancient Israelite religion, specifically as it pertains to monotheism/monolatry/polytheism, etc.

Extant texts within the corpus of epigraphic Hebrew have played a significant role in the development of thought concerning ancient Israelite Religion. It should be noted from the outset that there is a relative dearth of epigraphic Hebrew evidence, especially when compared to Mesopotamian and Egyptian archives of texts. We have no monumental or royal inscriptions in Hebrew from ancient Israel (the closest we can come would be to something like the Siloam Tunnel inscription—it is possible that this is an expression of Israelite understandings of the role and nature of the ruling class).
Some of the most notable examples of extant material, of course, come from sites such as Kuntillet Ajrud and Khirbet El Qom where we find various types of short blessings and petitions written on media like pithoi in ink. Many of these inscriptions appeal to “Yahweh of Teman” and “Yahweh of Samaria” for some kind of blessing and extension of life. These exemplars in particular grant us insight into the development of Israelite monotheism and the ANE phenomenon of the local manifestation of deities. As Sommer points out, local manifestations are not full manifestations of the deity where the deity is fully present in one and only one location (cf. Deuteronomy); but, rather, a fractalized understanding of the deity in question. Furthermore, the inscriptions from KAjr and KelQ raise the question of whether or not Yahweh had a consort—Asherah (אשרה, אשרתה). The greatest amount of controversy pertaining to this issue surrounds the form of אשרתה. Specifically, is this a reference to the goddess Asherah or is this a reference to some kind of cultic object and/or tree? The most obvious crux is the presence of the 3ms pronominal suffix. Zevit posits that this is a secondary feminization of the word. This linguistic phenomenon is not only rarely attested, but rather unconvincing. Sommer, on the other hand, does not believe that the suffix can be appended to a personal name—a tired and old argument that has been dispensed in numerous places (cf. Rollston, Writing and Literacy... 2010 and Mark Smith The Early History of God). If personal names can appear in the construct state (e.g., Dagon of Tuttel, Yahweh of Teman) and nouns are in construct with their possessive suffixes, then it stands to reason that the name אשרה can be in construct with a 3ms pronominal suffix. All that to say that in earlier permutations, these epigraphic sources tell us that Yahweh likely had a consort and that consort was Asherah.
The corpus of Old Hebrew ostraca have also been used in reconstructing the religions of early Israel. We not only see personal names with –yhw theophoric elements; but, we also see oath formulae that comparable in form to those found in the Hebrew Bible (“as Yahweh lives…”). On the other hand, we see a considerable number of theophoric elements such as b‘l, ’l, ’dn, etc. Onomastic evidence should be treated with caution. While naming practices could be indicative of religious thought or belief systems, they could also simply be a reflection of what people considered to be a nice name. We might readily compare the onomastic evidence from Elephantine and the papyri recovered there, where many have argued that the early Jews at the military outpost in the Nile practiced a syncretistic form of Yahwism where the Egyptian goat-god Khnum was also venerated. Also worth mentioning is the practice of ad nominem representation in the DH, where the author or redactor saw fit to change the name of Ishba‘al (“man of Ba‘l”) to Ishboshet (“man of shame”). The same can be seen in the change from Meriba‘al to Mephiboshet.
We might also readily consider things like stamp seals and jar handles recovered from archaeological digs in the Levant. While these do not give us much in the way of textual evidence, they still give us a glimpse into the material culture, its production and use, its role form an art historical perspective, and its role in social thought. One overarching characteristic of early Israelite religion possibly recoverable in this regard was aniconism of the deity. Outside of one possible interpretation of the drawings on the KAjr and KeQ pithoi (namely that the bull depicts Yahweh), deities were by and large not depicted. Occasionally a solar disk would be used, likely to indicate some kind of deity; however, unlike things like Assyrian cylinder seals, Yahweh was not usually portrayed. (We might readily consider comparative data like the Ain Dara sanctuary, where the deity is portrayed with strident footsteps moving forward out of the sanctuary.) The biblical text has been used to attempt to reconstruct the early religions of Israel. Used in this manner, the text should be treated with caution. Much of the biblical text presents a polemical and/or biased perspective on ancient Israelite religion. However, there are aspects of the text that provide data for us by which we may reconstruct certain aspects of the development of Israelite religions in antiquity. For example, we might readily consider the epigraphic evidence from Qumran in 4QDeutj, which offers us a variant to the MT of the Song of Moses in Deut 32:8-9. In these verses we see Elyon (the head of the pantheon) apportioning the peoples to junior deities, of whom Yahweh is one. MT reads ישראל בני while Qumran attests אלהים בני. In this particular permutation of Deuteronomy maintained at Qumran, we are given insight into early understandings of the Israelite pantheon where Yahweh was not the chief deity of the pantheon. Later in Job 1 we see Yahweh as having ascended to the chief position within a pantheon. It is not until later that full blown monotheism, as opposed to monolatry or henotheism, was really instantiated within Israel.