I came across this fantastic blog post, refuting the YEC model of the patriarch lifespans. Did you know that the genealogy in Genesis 5 is not a literal numerical account of the antediluvian lifespans of Adam to Noah? Instead, a remarkable numerical schema is revealed when the lifespans from Adam to Moses are added together: 12,600 years. This schema has eschatological connotations that relates to the 1,260 days mentioned in Daniel and Revelation. And outside the bible, the famous War Scroll (1QM) from Qumran says that the Sons of Light will fight the Sons of Darkness for a period of 35 years. In the lunisolar calendar, this equals to 12,600 days!
Also, the following is an absolutely fascinating excerpt from this paper cited in the blog post:
The figure 12,000 is another important schematic number in early Judaic-Christian eschatological traditions. 12,000 is associated with the tribe of Joseph, indeed with each of the 12 tribes of Israel in Revelation 7:8 as the number from each tribe who will be sealed and redeemed in the final days. Adding the tribes together produces the total of 144,000 (Rev 7:4; 14:1), which corresponds to the number of months in a 12,000-year period. Based on 1 Kings 7:26, 144,000 is the volume (in logs) of 'the sea' (as the ritual bath or mikvah is called) of the first temple (one bath being equal to 72 log). This bath is said to have stood on a base consisting of twelve oxen, probably representing the twelve tribes of Israel. In Revelation this imagery has been transposed to the 144,000 sealed servants (Rev 14:1) who sing the song of Moses and the song of the Lamb (i.e. Jesus) next to the glass 'sea' of fire (Rev 15:2-3). The notion of the righteous being purified in a divine fire was a key element of Christ's return (Luke 3:16).
It seems likely, then, that the Christian author of Revelation was drawing on an earlier Jewish chronological tradition centering on the 12,000/144,000 motif, one that according to the reconstruction offered here, was central to the progenitor lifespan chronology. This chronological tradition was certainly extant in apocalyptic traditions throughout the ancient Near East. Zoroastrian tradition viewed the duration of the world as 12,000 years. According to this tradition, the end of the 12,000-year period marks the cessation of the struggle between good and evil (which lasts for 6,000 years), the raising of the dead and Judgement Day.
The notion that the 12,000/144,000 chronological motif was adopted by Jewish chronologers from the Indo-Iranian mytho-religious traditions is a tempting hypothesis. The most likely place of diffusion is Babylon during the Persian era (6th-4th centuries BCE). Several scholars contend that it was during this time, when the diasporic Jewish community flourished in that region, that Jewish writers came to be influenced by Zoroastrianism apocalyptic teachings.