Why was arabia an unknown world for most of record history

For most of the recorded history, or more specifically till around the period of the expansion of the Arabian Empire, it was a relative unknown for most of the the other countries. It is not that the others didn't knew the region, but the region was not of interest of any of the other countries so it was left mostly unexplored. This was due to several reasons:

- The landscape; it was and still is a desert dominated region, so it was dangerous and unattractive for most people.

- The population; there was a very small population which was predominantly nomadic so it was not of great use for the foreign countries.

- Scarcity of resources; Arabia lacked any significant resources that can increase an interest in the region, and the biggest problem of all was the lack of water since the Arabian Peninsula doesn't have a single constant river flow.

well that depends on how deep the hole is. you'd first go through te crust of the earth, then the upper mantle, then the lower mantle then the outer core, then the inner cor then you'd be stuck in the core to melt.