The Halfan culture flourished along the Nile Valley of Egypt and Nubia between 18,000 and 15,000 BC, though one Halfan site dates to before 24,000 BC.[lower-alpha 1] People survived on a diet of large herd animals and the Khormusan tradition of fishing. Greater concentrations of artifacts indicate that they were not bound to seasonal wandering, but settled for longer periods.[9] They are viewed as the parent culture of the Ibero-Maurusian industry,[lower-alpha 1] which spread across the Sahara and into Spain. The Halfan culture was derived in turn from the Khormusan,[lower-alpha 2][11] which depended on specialized hunting, fishing, and collecting techniques for survival.