The Supplier of Your Supplier

If you are a business owner, no doubt you are familiar with your suppliers.  But how familiar are you with your supplier’s supplier?  This may seem unrealistic in some cases, because some supply chains can be Biblically long.  Ore begat the mining company begat refiners, and on and on until you get those lovely copper pans in your kitchen pantry.  So, more precisely, what is the link (or links) in your supply chain that have the most significant impact on price and/or availability of key inputs?